A lumber order usually goes wrong when the calculator and invoice use different size conventions. A yard may quote board feet from nominal or tally dimensions even though the surfaced stock is smaller, while retail framing lumber may instead be priced by the piece or linear foot. Board feet measure a billed volume convention, not structural capacity. Enter the count, seller's billed/tally length, width, thickness and board-foot price here, and confirm that basis on the quote before relying on the cost.
Nominal tally versus the wood you carry home
One board foot is a tally unit equivalent to a piece 1 inch thick, 12 inches wide and 12 inches long. That is 144 cubic inches, one twelfth of a cubic foot, 12 board feet per cubic foot, and 0.002359737 cubic metres. This calculator divides the volume represented by the entered seller-billed dimensions by that constant. Many North American board-foot invoices use nominal or tally dimensions, but practices vary by product and seller, so the quote controls. Published conversion tables put a surfaced dry 2 by 4 at 0.0365 cubic feet per lineal foot, while a nominal 2 by 4 tally represents 0.0556 cubic feet per lineal foot. Entering the surfaced measurements against a nominal invoice would understate the billed tally by about one third.
| Nominal size (in) | Board feet per lineal foot | Surfaced dry (cu ft per ft) | Rough dry (cu ft per ft) |
|---|---|---|---|
| 1 x 4 | 0.3333 | 0.0182 | 0.0220 |
| 1 x 6 | 0.5000 | 0.0286 | 0.0342 |
| 1 x 8 | 0.6667 | 0.0378 | 0.0448 |
| 1 x 10 | 0.8333 | 0.0482 | 0.0570 |
| 1 x 12 | 1.0000 | 0.0586 | 0.0691 |
| 2 x 4 | 0.6667 | 0.0365 | 0.0409 |
| 2 x 6 | 1.0000 | 0.0573 | 0.0635 |
| 2 x 8 | 1.3333 | 0.0755 | 0.0832 |
| 2 x 10 | 1.6667 | 0.0964 | 0.1058 |
| 2 x 12 | 2.0000 | 0.1172 | 0.1284 |
Source: Rural Technology Initiative, University of Washington, Forest Products Measurements and Conversion Factors, Chapter 4: Lumber.
Board feet are tallied on nominal size, while the volume columns are the solid wood actually present in one lineal foot. The gap between the two columns is the drying and planing loss you pay for.
Taking the billed dimensions from the seller's quote
- Count pieces, never bundles. Count individual boards and write the number down before anything is moved. Banded units are made up at the mill and often hold an odd count, so a unit sold as 50 pieces can arrive with 48. Recount after unloading and use that figure. Tool: Tally sheet.
- Record the billed/tally length. Copy the length basis from the quote or invoice. If the seller bills an 8 foot tally length, enter 2.4384 metres in Metric mode or 8 feet in Imperial mode even when a tape reading differs slightly. Use a measured length only when the seller confirms that measured/full dimension is the billing basis. Tool: Quote or invoice.
- Record the billed/tally width. Copy the width the seller uses for the board-foot tally. Dimension lumber is often billed at nominal width, while random-width hardwood rules and full-dimension mill stock can differ. Do not substitute a caliper reading for a nominal invoice; ask the seller which width appears in the tally. Tool: Quote, invoice, or tally sheet.
- Record the billed/tally thickness. Copy the thickness basis from the quote. A nominal 1 inch board may arrive near 0.0206 metres after surfacing yet still be tallied at 0.0254 metres. Entering the surfaced thickness against that invoice would understate board feet about 18.9 percent. Measure actual thickness for a cut list, but use it in this purchasing calculator only when the seller bills actual/full dimensions. Tool: Quote or invoice; caliper for a separate cut-list check.
- Read the price basis off the tag. Check whether the shelf tag prices the board foot, the lineal foot or the piece, then convert before entering anything. A 2 by 6 holds exactly 1 board foot per lineal foot, so those two prices look identical for that one size and diverge for every other size.
- Set waste from the cutting list. Take the waste percent from your own cutting list instead of a habit. Repetitive parts cut from long stock waste little, while short parts cut around defects in random length hardwood commonly waste far more than the 10 percent starting value in the form.
Hardwood by the quarter, softwood by the stick
Softwood framing is bought by the piece and only converted to board feet on the invoice. Hardwood is the opposite: it is sold by the board foot, in random widths, and its thickness is quoted in quarters of an inch. Four quarter stock is nominally 1 inch, and the reference tables give a manufactured rough green thickness of 1 3/16 inches, a surfaced two sides thickness of 13/16 inch, and a permitted tolerance of 1/4 inch. Eight quarter stock is nominally 2 inches, with a rough green thickness of 2 7/16 inches, a surfaced thickness of 1 3/4 inches, and a tolerance of 3/8 inch. Hardwood lengths run from 4 to 16 feet in 1 foot steps, no more than half the pieces in a shipment may be odd lengths, and any fraction of a foot is dropped when length is recorded. Enter the rough thickness the seller is billing you for, then plan your cutting list around the surfaced thickness you will actually be able to use.
Pricing twelve eight-foot shelving boards
| Field | Value |
|---|---|
| count | 12 |
| length | 2.4384 |
| width | 0.1524 |
| thickness | 0.0254 |
| price | 4 |
| waste | 10 |
The quote bills twelve boards at tally dimensions of 8 feet long, 6 inches wide and 1 inch thick, entered in Metric mode as 2.4384, 0.1524 and 0.0254 metres. One billed board represents 96 by 6 by 1 inches, or 576 cubic inches; dividing by 144 gives exactly 4 board feet per board, and twelve boards give 48. At 4 dollars per board foot the material is 192 dollars, and the 10 percent allowance adds 19.20 dollars, for a total of 211.20 dollars. Count, length, width, and thickness each enter once, so a 10 percent change to any one changes board feet 10 percent when the others stay fixed. The largest real uncertainty is the seller's billing basis: substituting a surfaced 3/4 inch measurement for a 1 inch nominal tally would cut the calculated tally 25 percent even though the invoice may not change. Confirm whether the stock is actually sold per board foot, per piece, or per linear foot.
Result: 48 board feet; 211.20 cost.
Moisture content changes the size on the tag
Size and moisture are written into the same product standard, so a board can be legally sold at two different widths depending on how wet it was when it was planed. Softwood under 114 millimetres, that is nominal 5 inches, counts as dry once it has been seasoned to a maximum moisture content of 19 percent, and anything above that is green. A surfaced green 2 by 4 measures 1 9/16 by 3 9/16 inches and is cut oversize on purpose, because it shrinks to the standard dry size as it dries to roughly 15 percent moisture content. The class breaks follow the same standard: boards are thinner than 38 millimetres, dimension lumber runs from 38 millimetres up to 114 millimetres, and timbers start at 114 millimetres in the smallest dimension. Widths commonly run from 38 to 387 millimetres, or nominal 2 to 16 inches, and lengths come in multiples of 305 millimetres, with even 610 millimetre steps the usual retail stock.
Common mistakes
- Entering planed sizes while the seller writes the invoice on nominal sizes.
- A surfaced dry 2 by 4 holds 0.0365 cubic feet per lineal foot against a nominal tally of 0.0556, so measured sizes produce a total roughly one third below the figure the yard will charge. Ask which basis the price uses before you measure anything. Enter nominal sizes when the quote is a trade tally, and enter measured sizes only when the seller bills full dimension rough sawn stock.
- Mixing inches and metres across the four dimension fields.
- The form carries metre defaults such as 2.4384 and 0.1524, and a single field left in inches multiplies the volume by roughly 39 without producing any warning that the answer is wrong. Convert everything to one system before typing, then sanity check the result against 4 board feet for a single 8 foot piece of 1 by 6 stock before you trust the total.
- Treating the 10 percent waste value as a fixed rule for every cutting list.
- Waste depends on the cut pattern rather than the material. Long repetitive parts from softwood strip out with very little offcut, while short parts cut around knots in random width hardwood routinely lose far more. Lay out the actual cutting list against the lengths on offer, count the drops that are too short to reuse, and enter that measured percentage instead of the starting value.
- Buying board feet for a job that the store actually sells by the piece.
- Framing lumber, decking and studs are usually priced per piece at retail, so a board foot total is a costing figure that has no matching line on the shelf tag and cannot be handed to a salesperson. Convert the total back into whole pieces of the length the store stocks, then round up to the next piece, since no yard will cut a stick to fill a fractional board foot.
Frequently asked questions
Should I enter nominal or measured board sizes?
Use the dimensions on which the seller calculates the quote. Many board-foot tallies use nominal dimensions, so a quoted 2 by 4 may be billed as a full 2 inches by 4 inches even though the surfaced stock is smaller. Enter nominal sizes when that is the invoice basis. Enter measured dimensions only when the seller confirms a full-dimension or actual-volume basis; retail framing lumber may instead be priced per piece or linear foot.
Why is one board foot equal to 144 cubic inches?
The unit is defined as a piece 1 inch thick, 12 inches wide and 12 inches long. Multiplying those three numbers gives 144 cubic inches, which is one twelfth of a cubic foot and 0.002359737 cubic metres. That is why there are 12 board feet in a cubic foot, roughly 424 board feet in a cubic metre, and why 1,000 board feet works out to 83.33 cubic feet or 2.36 cubic metres.
Does the waste percent need to cover saw kerf too?
Yes, whenever the cut count is high enough to matter. Measure your own blade kerf on a scrap with a caliper, multiply it by the number of cuts in the list, and compare the result against the 2.4384 metre length of a standard 8 foot board. Add that share to your offcut losses rather than tracking it separately, because the form applies one combined percentage to the cost figure and to nothing else.
How do I price rough sawn stock from a small mill?
Small mills usually sell at full dimension, meaning a board called a 2 by 8 really measures close to 2 inches by 8 inches. In that case nominal and measured sizes agree, so enter the tape reading directly. Allow extra thickness for planing if the boards arrive rough, because taking a nominal 1 inch board down to a clean surface removes roughly 3/16 of an inch.
Can this result be used to size a joist or a beam?
No, and that separation matters. A board foot total tells you what the material costs and how much of it to load. Structural capacity comes from span tables and design values in the National Design Specification and the Wood Frame Construction Manual, which account for species, grade, spacing and load. Any load bearing member should be sized from those documents or by a qualified professional.
Where a board foot stops answering the question
Volume is a purchasing unit and nothing more. It tells you what a board-foot quote costs, not whether the pile will hold anything up. Span, joist depth, header sizing and connection design come out of the National Design Specification and the Wood Frame Construction Manual published by the American Wood Council, and no quantity result replaces them. Call a structural engineer or a licensed builder before you order material for a load bearing wall, a beam over a wide opening, a deck ledger fixed to a house, or anything that a permit drawing has to show. Rough sawn stock may be billed at full measured dimension, but that is not universal: use measured sizes only when the seller confirms that basis. Retail dimensional lumber is commonly priced per piece or linear foot, in which case the board-foot cost output is only a comparison and the invoice must be calculated in the seller's actual unit. Mill tally rounding can also differ, so compare the unrounded result with the quote.
Related calculators
Sources
- Forest Products Measurements and Conversion Factors, Chapter 4: Lumber Rural Technology Initiative, University of Washington. Supplies the 144 cubic inch board foot definition, the statement that board feet are calculated from nominal dimensions, the hardwood quarter thickness and tolerance figures, and every value in the table on this page. Accessed 2026-09-07.
- Wood Handbook Chapter 6: Commercial Lumber, Round Timbers, and Ties (FPL-GTR-282) USDA Forest Service, Forest Products Laboratory. Source of the 19 percent dry moisture limit, the 15 percent shrinkage point, the 38 and 114 millimetre thickness class breaks, the 38 to 387 millimetre width range and the 305 millimetre length multiple. Accessed 2026-09-07.
- Codes and Standards Publications American Wood Council. Confirms that span and load design for wood framing sits in the National Design Specification and the Wood Frame Construction Manual, which a board foot quantity result does not replace. Accessed 2026-09-07.
This is a planning result, not a supplier quote; sellers use different pack, bag, board, roll, and bundle conventions, so confirm the exact product label and selling unit before you order.