Fence Calculator — Posts, Rails and Post-Hole Mix

Posts, rails, boards and post-hole mix.

Showing US units

Posts to buy EXAMPLE14 posts4x4, at least 8 ft 3 in each, plus the depth of any stone base or soil capAlso: 46 bags (80 lb each) of QUIKRETE Concrete Mix, 39 boards (8 ft each, size not chosen) of rails and 219 boards (1x6, at least 6 ft each) of pickets

An answer marked EXAMPLE is worked out from the page’s sample values. Type your own over the values marked SAMPLE to make it yours.

ftSAMPLE

Measured from the center of the first post, or the wall the run starts from to the center of the last post, or the wall it stops at, along the ground, one straight line at a time. At a corner, count the corner post with the run before it: in the next run, that end meets a post already counted.

ftSAMPLE

Measured from the finished ground to the top of the fence. It is not the post length: the post also goes down into the hole, and the post length printed with the result works that out from the depth of mix. If a stone base goes under the mix or a soil cap over it, the post has to be longer by that much.

Nobody publishes this for a residential wood fence. These are four publishers, each named in its option, writing about four different kinds of fence, and they do not agree — so pick the one that applies where you are building, or ask your building department and type theirs.

Starts at 8 ft on center — the City of Fort Myers’ maximum for any fence but chain link, and the calculator’s pick among the four published spacings because two of the four publishers print 8 ft as a maximum, while the 4 ft spacing applies only in two Florida counties’ hurricane zone and the 10 to 12 ft spacing is for wire farm fences. Source

Fort Myers’ permit detail for all fence types except chain link, and Scappoose’s prescriptive set for a fence over 6 ft (1.8288 m).

Worth exactly one post at each end, and not arithmetic: it depends on whether that end stops at a corner, a house, or a post that is already standing or already counted in another run.

Nominal, as a yard sells it. What it really measures comes out of the national lumber standard, and the difference is what decides how much of the hole the post itself takes up.

Four published sizes, each named with the body that published it. Both bagged-mix makers say to dig about three times the post width, but neither says whether that is the nominal size or the real one — a difference of about thirty percent in what a hole swallows — so this page offers the widths publishers actually print instead of doing that multiplication for you.

Starts at 12 in — the County of San Diego’s recommendation for a wood fence post, and the calculator’s pick among the four published widths because it is what the bag makers’ “about 3 times the diameter of the post” gives when a 4x4 is measured by its name. Source

inSAMPLE

Measured from the bottom of the hole, or the top of any stone base in it to where the mix stops. With QUIKRETE Concrete Mix the 6 inches (152.4 mm) the maker puts under the post are part of this depth. The sample follows QUIKRETE’s method for its Concrete Mix at the sample’s 6 ft (1.8288 m) fence: a hole a third of the whole post deep, with 6 inches (152.4 mm) of mix under the post — a 33 in (838.2 mm) hole for a 99 in (2514.6 mm) post set 27 in (685.8 mm) deep. Not the depth of the hole if the top is being capped with soil: take that off first. Where the ground freezes, the depth that governs is the one in your building department’s adopted table, and no national table exists for it.

Two publishers state a count and they agree on three for an ordinary privacy fence — but they name different boards for it, so the count is here and the size is yours.

Starts at Three — the count the City of Hallandale Beach prints for a fence over 4 ft and up to 6 ft, and the City of Scappoose, Oregon, for one of 6 to 8 ft — both take in the sample’s 6 ft fence; the other two options are counts printed for lower and taller fences. Source

Nominal again. The count uses the width the board really is, out of the national lumber standard: a 1x6 is 5-1/2 in across, which is why a hundred-foot butted run takes 219 boards and not 200.

in

Measured from the edge of one picket to the edge of the next. A design choice, and this page will not make it. Zero is the butted privacy fence. The only published rule found anywhere sets the gap equal to the board width, and only for a front-yard picket fence no more than four feet (1.2 m) tall in Fort Myers, Florida.

The yields are not interchangeable, which is why this is a question. Each option carries its own maker’s published figure for what one bag makes, and the bag weight is printed on the answer so the order cannot be filled with the wrong size.

If it will, this calculator stops. At that point the openings and the height are safety limits published by a federal agency and set in local code, not numbers to choose.

Applies to Posts and Post-hole mix.

Starts at 0 spares — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for fence posts or for bags of post-hole mix, so the calculator adds none rather than invent one. Each step adds one post and one bag of mix. The spare post is for one that splits or warps before it is set, so it goes into a hole already counted; one bag is not enough mix for a new hole.

Applies to Post-hole mix.

0%

Starts at 0% — this calculator’s own starting point, not a published figure. No bag maker or building department this calculator cites prints an allowance for a hole that runs wide or a spilled bag, so the calculator adds none rather than invent one. Change it to how much mix to buy ahead for a hole dug wider than planned.

Applies to Rails.

Starts at 0 spares — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for rail boards, so the calculator adds none rather than invent one. Each step adds one rail board.

Applies to Pickets.

Starts at 0 spares — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for fence boards, so the calculator adds none rather than invent one. Each step adds one fence board.

Posts to buy EXAMPLE14 posts4x4, at least 8 ft 3 in each, plus the depth of any stone base or soil cap

Post length needed — the fence height plus the depth of mix, less the 6 in of mix under the post (add any base course under the mix or soil cap over it) 8 ft 3 in

Post-hole mix 46 bags (80 lb each) of QUIKRETE Concrete Mix

Rails 39 boards (8 ft each, size not chosen)

Pickets 219 boards (1x6, at least 6 ft each)

A 100 ft run 6 ft tall, on the spacing, hole, mix depth, rails and pickets entered above.

Posts — how the quantity was worked out
The job needs14 posts
Buying 14 posts (4x4, at least 8 ft 3 in each, plus the depth of any stone base or soil cap) covers14 posts
Left over0 posts

Each line is worked out on its own, so each can be checked on its own; the notes further down name the figures behind them.

Counted for one straight run of fence on level ground. Ground that slopes across the fence line, a fence on or near a retaining wall and a fence asked to hold anything up are not counted here.

Not counted in these quantities: gates and their hardware; a bigger or deeper post at a corner or end, and the extra mix its hole takes — the count gives every post the line-post size and depth; bracing; nails or screws for the rails and boards, and any rail hangers.

Sections between posts13

Post spacing this count used, center to center Source8.00 ft

Mix in one hole, with the post standing in it2.0 cu ft

Share of the fence line that is gap0 %

  • The post count above is worked from 8 feet between posts, which is the widest spacing on one city’s own standard fence detail, and also the widest on an Oregon city’s prescriptive plan set for a fence over six feet — two publishers, two states, the same figure. Nothing national publishes a spacing for a residential wood fence, so this is one publisher’s figure for one kind of fence rather than the trade’s answer, and the options above show how far apart the four of them are. Source
  • QUIKRETE’s method for this mix digs the hole a third of the whole post deep and stands the post on 6 inches of mix: for this 6 ft fence that is a 33 in hole and a 99 in post set 27 in deep. Read it as a third of the FENCE and the posts come out short. A county recommends 24 inches for a wood fence post, and one state’s hurricane-zone code requires 24 inches for a fence up to six feet, so the published depths disagree. Where the ground freezes, neither governs: the model code prints frost depth as a blank each jurisdiction fills in, so the number for a given address is in the adopted table of the building department that covers it. Source
  • The mix is worked out as the hole less the post standing in it, times the number of holes, divided by the yield the maker prints on the bag. That is the maker’s own method, and against one maker’s published post-setting table — 4 rows for a 10 inch hole — it lands within a fifth of a bag on every row. It only lands there because the post is subtracted and taken at its dressed size: subtracting it is what makes the error change sign across the table, where leaving the hole gross runs high on every row and four times worse in total. Two things it does not do: it does not take off the 4 to 6 inches of compacted stone that one maker puts in the bottom of the hole, or the 3 inches a county puts under the footing, because the depth above is the depth of MIX and taking a base course off is a subtraction this page leaves alone; and it does not stop 3 to 4 inches below the top of the hole the way one maker’s method does. QUIKRETE’s method for this mix stands the post on 6 inches of mix in the bottom of the hole, and the count includes that mix under each post. Source
  • Two publishers state a rail count, in two states and two climates, and they agree on 3 for an ordinary privacy fence and more when it is taller — and each names a board for the fence heights it covers: Hallandale Beach’s handout names nominal 2 x 4 rails for wood fences up to 6 ft, and Scappoose’s plan set names 2x6 rails laid on edge for fences over 6 ft. For a fence this tall, the publisher that covers it names 2 x 4 rails. The size is left open, and this page counts rails rather than specifying them. Every rail is counted at the full width of a bay, including the short last one, because a rail cut down fits and a rail cut short does not. Source
  • The rails are cut from the 8 to 20 ft (2.4 to 6.1 m) lengths South Coast Lumber Co., a sawmill, states it manufactures, stepped in the two feet the national lumber standard permits, which can only ever round a board up. The Southern Pine Inspection Bureau publishes a wider range, 6 to 24 ft (1.8 to 7.3 m), and at every spacing this page offers by name that range buys the same footage of rail in longer boards with more saw cuts, so the page does not ask which range a yard carries. A typed spacing can break the tie: eleven-foot bays come two to a 22 ft (6.7 m) board with nothing left, where a range stopping at 20 ft buys 12 ft (3.7 m) boards and one foot in twelve of the rail line is offcut. The American Wood Council prints a standing footnote under its span tables to check sources of supply for lengths over 20 ft before planning around them. Source
  • How far apart the boards go is a design choice, and this page will not make it. The one published rule found anywhere is one city’s: where a uniform 50 percent void is required of a front-yard picket fence no more than four feet tall, the gap must equal the board width. Everything else that city publishes is 75 percent, and it prints no gap rule for that at all. A zero gap is the butted privacy fence and needs no source, because it is the case with nothing between the boards. Source
  • Each picket is counted as one board running the full height of the fence above the ground, so the boards are given as at least that long. A gap left at the ground, or a cap rail laid over the boards, makes a board a little shorter; this page takes neither off and does not pick a stock length for the boards.
  • The board count uses the width a board really is, out of the national lumber standard: a nominal 1x6 is 5-1/2 inches across, not 6. Two things that width is not. It is a minimum at the time of manufacture, and the standard says in the same clause that lumber moves with its moisture. And it is the DRY column: the standard excepts redwood, western red cedar and northern white cedar from its green sizes and sets a different width for them, which is exactly what fence boards are usually made of — so an unseasoned cedar board is a little wider, and over a long run that is a board or two fewer than the count above. Source
  • This is a material list, not a compliance check. Every published figure behind it is in the source list below, with the body that published it; the ordering margins are not published figures, and the page says so where they are set. None of them is a statement about a particular address: whether a fence of this height, on this spacing, on this footing is allowed at a given site is that building department’s answer, along with setbacks, permits and which side the good face has to look at.

The printed list carries every quantity, the post length, and the conditions they were worked from.

Fence Calculator — Posts, Rails and Post-Hole Mix

ConcreteTally

EXAMPLE — not a measured job. Every quantity below is worked out from this page’s sample measurements. Enter the real measurements and print it again before anyone orders from it.

Job / customer
Deliver to

Post length needed — the fence height plus the depth of mix, less the 6 in of mix under the post (add any base course under the mix or soil cap over it): 8 ft 3 in

What to buy

MaterialBuyWhich isLeft over
Posts14 posts (4x4, at least 8 ft 3 in each, plus the depth of any stone base or soil cap)14 posts0 posts
Post-hole mix46 bags (80 lb each) of QUIKRETE Concrete Mix27.6 cu ft0.0 cu ft
Rails39 boards (8 ft each, size not chosen)312 ft0 ft
Pickets219 boards (1x6, at least 6 ft each)219 boards0 boards

Rails: cut 39 pieces of 8 ft — 1 from each 8 ft board, leaving nothing on each.

Counted for one straight run of fence on level ground. Ground that slopes across the fence line, a fence on or near a retaining wall and a fence asked to hold anything up are not counted here.

Not counted in these quantities: gates and their hardware; a bigger or deeper post at a corner or end, and the extra mix its hole takes — the count gives every post the line-post size and depth; bracing; nails or screws for the rails and boards, and any rail hangers.

This sheet does not say the fence complies with anything. Every published figure behind it is in the source list at the end of this sheet, with the body that published it, and whether a fence of this height on this spacing is allowed at a particular address is a building department’s answer. The rail size is not on this sheet because this calculator does not choose it: one city’s handout names nominal 2 x 4 rails for wood fences up to 6 ft and another’s plan set names 2x6 laid on edge for fences over 6 ft, so the rails are counted and not specified. Write the size in the blank below. The board size row above it is the pickets.

Rail size to buy — this calculator does not choose it

Worked out from

Length of the runMeasured from the center of the first post, or the wall the run starts from to the center of the last post, or the wall it stops at, along the ground, one straight line at a time.100 ft (sample)
Height of the fence above the groundMeasured from the finished ground to the top of the fence.6 ft (sample)
How far apart the posts go8 ft on center — Fort Myers, Florida, and Scappoose, Oregon
Does the run need a new post at each end?Yes — a new post at each end
Post size4x4 — the usual post, 3-1/2 in square dressed
Hole width across12 in — San Diego County’s recommendation for a wood fence post
How deep the mix will sit in the holeMeasured from the bottom of the hole, or the top of any stone base in it to where the mix stops.33 in (sample)
Rails in one sectionThree — Hallandale Beach up to 6 ft, Scappoose 6 to 8 ft
Picket board size1x6 — 5-1/2 in across dressed
Gap between picketsMeasured from the edge of one picket to the edge of the next.0 in
Which bag you are buyingQUIKRETE Concrete Mix (80 lb bag)
Will this fence enclose a pool, spa or hot tub?No
Amount needed — Posts14 posts
Amount needed — Post-hole mix27.6 cu ft
Amount needed — Rails312 ft
Amount needed — Pickets219 boards
Spare posts and bags of mix — Postsnone — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for fence posts or for bags of post-hole mix, so the calculator adds none rather than invent one.
Spare posts and bags of mix — Post-hole mixnone — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for fence posts or for bags of post-hole mix, so the calculator adds none rather than invent one.
Extra mix for a hole that runs wide — Post-hole mixnone — this calculator’s own starting point, not a published figure. No bag maker or building department this calculator cites prints an allowance for a hole that runs wide or a spilled bag, so the calculator adds none rather than invent one.
Spare rail boards — Railsnone — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for rail boards, so the calculator adds none rather than invent one.
Spare fence boards — Picketsnone — this calculator’s own starting point, not a published figure. None of the makers, codes or extension services this calculator cites prints a spare allowance for fence boards, so the calculator adds none rather than invent one.

Estimates only — check quantities before you buy. Confirm with your fence supplier, and your local building official for any permit or setback rule before ordering.

Where these figures come from

A number in brackets after a figure on this sheet is its entry in this list.

  1. What one bag of the fast-setting mix makes, 50 lb bag (Product data sheet, page 1 of 2, left column, heading YIELD, immediately below SIZES — first bullet. Partial quote: the block runs to five bullets and the fifth is a worked post-setting example, which has its own entry. — read with the SIZES heading above it); What one bag of the fast-setting mix makes, 60 lb bag (Product data sheet, page 1 of 2, left column, heading YIELD — second bullet of five. — read with the SIZES heading above it) — The Quikrete Companies, LLC, Manufacturer or grower specification. Effective from November 2025. The page-2 footer prints "Revised November 2025" and no day. Retrieved October 11, 2026.
  2. The maker's own worked example for one post hole (Product data sheet, page 1 of 2, left column, heading YIELD — fifth and final bullet of the block.) — The Quikrete Companies, LLC, Estimating chart (approximate). Effective from November 2025. The page-2 footer prints "Revised November 2025" and no day. Retrieved October 11, 2026.
  3. What one bag of the ordinary mix makes, 80 lb bag (Product data sheet, page 1 of 2, heading YIELD — the 80 lb line of five; the PRODUCT USE list on the same page includes "Pipe and post footings". — read with the title block and the SIZES heading above it); QUIKRETE's own method for setting a fence post with its 80 lb Concrete Mix (Product data sheet, page 2, "Method for Setting Fence Posts", sentences 1 to 6) — The Quikrete Companies, LLC, Manufacturer or grower specification. Effective from October 2022. The sheet prints "Revised October 2022" and no day. Retrieved October 11, 2026.
  4. What one bag of the second maker's fast-setting mix makes, 50 lb bag (Technical datasheet, page 1 of 2, left column, "Yield/Water/Coverage:" — the Bag Size / Yield / Water row, plus the coverage sentence beneath it.) — Sakrete (SAKRETE of North America LLC), Manufacturer or grower specification. Effective from May 2018. The page-2 footer prints "Rev. 05/18" and a 2018 copyright line, so month is the most the document states. Retrieved October 11, 2026.
  5. Hole width the maker's published post-setting bag table assumes (inches) (Technical datasheet, page 1 of 2, left column, under the printed heading "Post Setting - Based on Average 10" Diameter Hole:", laid out as two rows of two cells.) — Sakrete (SAKRETE of North America LLC), Estimating chart (approximate). Effective from May 2018. The page-2 footer prints "Rev. 05/18" and a 2018 copyright line, so month is the most the document states. Retrieved October 11, 2026.
  6. Post spacing, embedment and footing width for a wood fence up to six feet — one state code's prescriptive minimums (Single-page handout, the block headed "FBC 2017 Section 2328: HIGH VELOCITY HURRICANE ZONES: WOOD FENCES", clauses 2328.2 and 2328.3 reproduced in full.) — City of Miramar, Florida — Building, Planning & Zoning Department, Government publication. The form's own stamp reads "Wood Fence Rev 012/2017", which is not a date that can be read without guessing at the month; the code edition it reproduces is the 2017 Florida Building Code. Current as of the retrieved date. Retrieved September 13, 2026.
  7. Widest post spacing on one city's standard fence detail — 8 ft (Standard Detail F-3 (PDF page 3 of 6), title block "STANDARD FENCE DETAIL (ALL TYPES - EXCEPT CHAIN LINK)" — the dimension callout.); The one published rule for how far apart fence boards go (Standard Detail F-6 (PDF page 6 of 6), callout and its asterisk footnote on "EXAMPLE: PICKET FENCE DETAIL (Elevation View)" — the detail itself is drawn at 42 inches maximum.) — City of Fort Myers, Florida — Planning Division, Government publication. The detail sheets carry no publication or revision date of their own. Current as of the retrieved date. Retrieved September 13, 2026.
  8. Widest post spacing on one city's prescriptive plan set for tall fences — 8 ft ("DETAILS FOR FENCES OVER 6 FEET AND UP TO 10 FEET", page 4 of 5 — the standing note printed under the heading of TABLE 1.) — City of Scappoose, Oregon — Community Development Center, Government publication. The handout carries no publication or revision date on the page cited. Current as of the retrieved date. Retrieved September 13, 2026.
  9. Line-post spacing an extension service states for farm fencing — 10 to 12 ft (Fences for the Farm, Circular 774 — section "Fence Post Setting".); Shallowest an extension service says to set a wooden line post (inches) (Fences for the Farm, Circular 774 — section "Fence Post Setting", the wooden-post depth sentence.) — University of Georgia Cooperative Extension, University extension service. Effective from March 12, 2024. The publication line reads "Published with Full Review on March 12, 2024". Retrieved September 13, 2026.
  10. How deep and how wide one maker says to dig, and where the mix stops (Product data sheet, PAGE 2 of 2, APPLICATION, "Method for Setting Posts" — sentences 1, 2 and 4 of an eleven-sentence paragraph for the geometry, and sentence 9 for the soil cap. The paragraph ends "Wait 4 hours before post is subjected to any strain.") — The Quikrete Companies, LLC, Manufacturer or grower specification. Effective from November 2025. The page-2 footer prints "Revised November 2025" and no day. Retrieved September 13, 2026.
  11. The same digging rule from a second maker, with a stone base in the bottom of the hole (Technical datasheet, page 1 of 2, RIGHT column, section "Posts and Poles:", numbered step 1.) — Sakrete (SAKRETE of North America LLC), Manufacturer or grower specification. Effective from May 2018. The page-2 footer prints "Rev. 05/18" and a 2018 copyright line, so month is the most the document states. Retrieved September 13, 2026.
  12. Footing diameter a county recommends for a wood fence post (inches) (Form PDS 070, page 1 of 2, section WOOD FENCES — the first bullet and its sub-bullets.) — County of San Diego — Planning & Development Services, Building Division, Government publication. Effective from January 1, 2023. The form's own stamp reads "REV: 01/01/2023", a full date. Retrieved September 13, 2026.
  13. Footing diameters one city offers for a fence over six feet, with the depth each one buys (inches) ("DETAILS FOR FENCES OVER 6 FEET AND UP TO 10 FEET", page 4 of 5, TABLE 1 "FENCE POST, FOOTING SIZE AND DEPTH", column 4.); How many rails one city's prescriptive plan set requires, by fence height ("DETAILS FOR FENCES OVER 6 FEET AND UP TO 10 FEET", page 4 of 5: the prose paragraph headed "POST, RAILS, AND FOOTING SIZES" and TABLE 1 "FENCE POST, FOOTING SIZE AND DEPTH" that follows it, read with the title at the head of every page.) — City of Scappoose, Oregon — Community Development Center, Government publication. The handout carries no publication or revision date on the page cited. Current as of the retrieved date. Retrieved October 11, 2026.
  14. Fewest horizontal rails one municipality requires on a wood fence up to six feet ("INSTALLATION REQUIREMENTS FOR WOOD / CHAIN LINK FENCES", page 1 of 2, numbered item 3 under "Wood fences not exceeding six (6) feet in height may be constructed to meet the following minimum requirements:".) — City of Hallandale Beach, Florida — Building Division, Government publication. The handout carries no printed publication or revision date. Current as of the retrieved date. Retrieved October 11, 2026.
  15. What a post sold as a nominal 4x4 actually measures, surfaced and dry (Voluntary Product Standard PS 20-20, Table 3 "Nominal and minimum-dressed sizes of boards, dimension, and timbers", Dimension block — the nominal 4 in thickness and nominal 4 in width rows, printed page 16 (PDF page 16). Clause 5.2, printed page 13, is what makes the table binding.); What a post sold as a nominal 4x6 actually measures, surfaced and dry (Voluntary Product Standard PS 20-20, Table 3, Dimension block — the nominal 4 in thickness row read with the nominal 6 in width row, printed page 16 (PDF page 16).); What a fence board sold as a nominal 1x4 actually measures across, surfaced and dry (Voluntary Product Standard PS 20-20, Table 3, BOARDS block — the nominal 4 in width row, printed page 16 (PDF page 16).); What a fence board sold as a nominal 1x6 actually measures across, surfaced and dry (Voluntary Product Standard PS 20-20, Table 3, BOARDS block — the nominal 6 in width row, printed page 16 (PDF page 16).) — U.S. Department of Commerce, National Institute of Standards and Technology — Voluntary Product Standard PS 20-20, American Softwood Lumber Standard, Government publication. Effective from 2020. PS 20-20 carries the year 2020 in its designation; the document cited is that edition. Retrieved October 11, 2026.
  16. Void a city requires of a picket fence, by yard and by height (percent) (Standard Detail F-4 (PDF page 4 of 6), "PLANNING DIVISION GUIDELINES (Land Use Regulations – City Code 118.3.8)" — the front yard / corner lot and rear, side and waterfront bullets.) — City of Fort Myers, Florida — Planning Division, Government publication. The detail sheets carry no publication or revision date of their own. Current as of the retrieved date. Retrieved October 11, 2026.
  17. Maximum openings and minimum height a federal agency publishes for a pool barrier (inches) (Safety Barrier Guidelines for Residential Pools (CPSC Pub. 362), the numbered list under "Outdoor Swimming Pools", printed pages 15-16 (PDF pages 17-18), guidelines 1, 2, 4 and 7.) — U.S. Consumer Product Safety Commission, Government publication. No publication or revision date is printed on the pages cited. Current as of the retrieved date. Retrieved September 13, 2026.
  18. Standard lumber lengths — multiples of one foot or two feet (Voluntary Product Standard PS 20-20, clause 5.3.1 "Standard" under 5.3 Lengths, printed page 13 (PDF page 13)) — U.S. Department of Commerce, National Institute of Standards and Technology — Voluntary Product Standard PS 20-20, American Softwood Lumber Standard, Government publication. Effective from 2020. PS 20-20 carries the year 2020 in its designation; the document cited is that edition. Retrieved August 28, 2026.
  19. A board is never shorter than the length it is sold as (Voluntary Product Standard PS 20-20, clause 5.3.2 "Trimmed", printed page 13 (PDF page 13)) — U.S. Department of Commerce, National Institute of Standards and Technology — Voluntary Product Standard PS 20-20, American Softwood Lumber Standard, Government publication. Effective from 2020. PS 20-20 carries the year 2020 in its designation. Retrieved August 28, 2026.
  20. Lengths one sawmill manufactures its green Douglas fir dimension lumber in — 8 to 20 ft (Green Doug Fir Timbers, Dimension & Studs — mill capability paragraph) — South Coast Lumber Co., Manufacturer or grower specification. A mill's product page carries no commencement date; current as of the retrieved date. Retrieved August 28, 2026.
  21. Length range a grading agency states dimension lumber is available in — 6 to 24 ft (Nominal Vs Actual Lumber Sizes — the paragraph on lumber lengths) — Southern Pine Inspection Bureau, Industry technical article. The article carries no commencement date; current as of the retrieved date. Retrieved August 28, 2026.
  22. Lengths over 20 ft need their supply confirmed before you plan around them (Span Tables for Joists and Rafters, 2024 Edition — the standing footnote printed beneath every span table (PDF page 19 is Table R-1)) — American Wood Council, Trade association standard. Effective from 2024. The document is titled the 2024 Edition; it carries no month or day. Retrieved August 28, 2026.

This list, with a link to each document: concretetally.com/fence-post-calculator/#sources-heading

Every table ConcreteTally reads, with its dates: concretetally.com/sources

Local rules differ — ask your building department.

Where these figures come from

Every table ConcreteTally reads, with its dates: all sources.