Board-foot overview
A board foot is the standard unit lumber is bought and sold by in North America: a volume equal to a 1 inch × 12 inch × 12 inch board, or 144 cubic inches. This calculator turns any board's thickness, width, length and quantity into board feet, true volume and cost, and sums a whole cut list into one live take-off.
The one number people get wrong is which dimensions the board foot uses. Softwood dimensional lumber is billed by its nominal size (a 2×4 counts as 2 by 4), hardwood is billed by its rough quarter thickness, and only custom stock uses the size you actually measure. This tool keeps those rules straight so the figure matches the yard's. Everything runs in your browser; nothing you type is uploaded.
How this calculator works
Pick your units, then add a board for each size in the job. Choose softwood, hardwood or custom, set the length and quantity, and the results rail updates live with board feet, volume and — once you add a price — cost. Add a waste allowance and the tool also gives you the whole boards to buy.
How to calculate board feet
- Choose units & currencyPick metric or imperial and, if you'll price the job, your currency. Board feet are shown in either system.
- Add your boardsAdd a row for each size in the cut list, with its length and quantity. Give each a label to keep the take-off readable.
- Pick softwood, hardwood or customChoose a softwood preset (2×4, 1×6…), a hardwood quarter plus a width, or enter a custom thickness and width. This sets which dimensions bill the board feet.
- Set a waste allowanceEnter a waste percentage (10% by default) for cuts, offcuts and defects. The take-off adds it to the totals and to the boards-to-buy count.
- Add prices (optional)Choose a basis — per board foot, per lineal foot or per piece — and enter one price to estimate the material cost.
- Read the take-offUse the total board feet, volume, boards to buy and cost to order lumber. Export CSV or print the take-off for the yard.
What is a board foot?
One board foot is a piece of lumber one foot long, one foot wide and one inch thick — 144 cubic inches of wood. Any board with the same volume is one board foot: a 1×12 that is one foot long, a 2×6 that is one foot long, or a 1×6 that is two feet long all equal one board foot.
Board feet measure volume, not surface area or length, which is why a longer or thicker board is worth more of them.
12 in × 12 in × 1 in = 144 in³ = 1 board foot
The board-foot formula
Every figure in the take-off comes from these formulas. Lengths are converted to a common unit internally, so metric and imperial agree.
The engine uses these formulas; each is checkable by hand.
Board feet
bd ft = (nomThick_in × nomWidth_in × lengthFt) / 12- Uses nominal inch dimensions — the size the lumber is sold as, not the milled size.
- Hardwood uses the rough quarter thickness (4/4 = 1 in) with the measured width.
True volume
volume = actualThick × actualWidth × length- Uses the actual (dressed) dimensions, so it is smaller than the nominal size implies.
- Reported in ft³ (imperial) or m³ (metric).
Waste & boards to buy
totalWithWaste = total × (1 + waste) ; boardsToBuy = ⌈qty × (1 + waste)⌉- Waste is applied continuously to the board-foot, volume and lineal totals.
- Boards to buy round each row up to whole boards, then sum.
Cost
cost = quantityWithWaste × price- Quantity is board feet, lineal feet or pieces depending on the basis you pick.
- Cost stays blank until a price is entered.
Nominal vs actual size
Softwood is sold under a nominal name — a 2×4, a 1×6 — that is bigger than the board you take home. Drying and planing (surfacing) shave it down: a nominal 2×4 is actually about 1½ × 3½ inches. Board feet are always billed on the nominal size, so a 2×4 counts as a full 2 by 4 even though the wood is smaller.
The calculator uses the nominal size for board feet and the actual dressed size for volume, so both numbers are right. The comparison below shows the gap for a 2×4.
Softwood, hardwood & quarters
Softwood dimensional lumber (framing and boards like 2×4 or 1×6) uses the nominal inch sizes above, and comes in a fixed set of widths. Pick the size from the preset list and the tool fills the nominal and actual dimensions for you.
Hardwood is sold in random widths and in quarter thicknesses — 4/4 ("four-quarter") is one inch rough, 5/4 is 1¼ inch, 8/4 is two inches. Board feet are billed on the rough quarter thickness, before the board is surfaced, so you pay for the sawn thickness even after planing. Enter the quarter and the actual width you measured, and the calculator bills the board feet on the rough thickness while showing the surfaced size for volume.
Board feet per lineal foot
A handy reference: how many board feet each common softwood size holds per foot of length, and per 8-foot board. These come straight from the calculator's engine, so a hand check will match the tool.
| Size | Bd ft / ft | Bd ft / 8 ft board |
|---|---|---|
| 1×2 | 0.167 | 1.33 |
| 1×3 | 0.250 | 2.00 |
| 1×4 | 0.333 | 2.67 |
| 1×6 | 0.500 | 4.00 |
| 1×8 | 0.667 | 5.33 |
| 1×10 | 0.833 | 6.67 |
| 1×12 | 1.000 | 8.00 |
| 2×2 | 0.333 | 2.67 |
| 2×4 | 0.667 | 5.33 |
| 2×6 | 1.000 | 8.00 |
| 2×8 | 1.333 | 10.67 |
| 2×10 | 1.667 | 13.33 |
| 2×12 | 2.000 | 16.00 |
| 4×4 | 1.333 | 10.67 |
| 6×6 | 3.000 | 24.00 |
Pricing lumber
Lumber is priced three different ways, and this tool covers all of them. Hardwood and rough stock are usually sold per board foot. Softwood boards are often tagged per lineal (running) foot at a given size. And many yards just price common items per piece — so much for an 8-foot 2×4.
Set the basis that matches your quote, enter one price, and the estimate multiplies it by the matching quantity — board feet, lineal feet or pieces — all after waste. Leave the price blank to skip cost entirely.
Waste & overage
Cuts, defects, splits and end-trim mean you buy more wood than the finished job needs. The default 10% waste is applied to the board feet, volume and lineal totals so the estimate reflects what you actually purchase.
Because you can't buy a fraction of a board, the tool also rounds each row up to whole boards including waste, and sums them into the boards-to-buy count.
Worked examples
Two take-offs that show the formulas in action. Follow them to reproduce the numbers by hand.
Two illustrative take-offs. Follow the formulas above to reproduce the numbers.
Ten 8 ft 2×4 studs
Softwood- Given
- 10 pieces of 2×4 softwood, 8 ft long
- 10% waste, priced at 0.75 per lineal foot
- Formula
bd ft = (2 × 4 × 8) / 12- Steps
- Board feet per piece = (2 × 4 × 8) / 12 = 5.33
- Total board feet = 5.33 × 10 = 53.3
- With 10% waste = 58.7 board feet
- Boards to buy = ⌈10 × 1.1⌉ = 11
- Lineal feet = 8 × 10 = 80 (88 with 10% waste)
- Cost = 88 lineal ft × 0.75 = 66.00
- Result
- 53.3 board feet · 80 lineal feet (88 with waste) · 11 boards to buy · 66.00 cost
Four 4/4 walnut boards, 6 in × 8 ft
Hardwood- Given
- 4 boards of 4/4 (1 in rough) hardwood, 6 in wide, 8 ft long
- 10% waste, priced at 8.00 per board foot
- Formula
bd ft = (1 × 6 × 8) / 12- Steps
- Board feet per board = (1 × 6 × 8) / 12 = 4.0 (billed on the rough 1 in quarter)
- Total board feet = 4.0 × 4 = 16.0
- With 10% waste = 17.6 board feet
- Boards to buy = ⌈4 × 1.1⌉ = 5
- Cost = 17.6 board feet × 8.00 = 140.80
- Result
- 16.0 board feet · 17.6 with waste · 5 boards to buy · 140.80 cost
Common mistakes
The usual errors are using the actual (surfaced) size instead of the nominal size for board feet, forgetting hardwood is billed on the rough quarter thickness, confusing lineal feet with board feet, and leaving off a waste allowance. The calculator handles each of these, but every assumption is shown so you can check it.
Frequently asked questions
Common questions about calculating and buying lumber by the board foot.
How do you calculate board feet?
Multiply the nominal thickness in inches by the nominal width in inches by the length in feet, then divide by 12: bd ft = (T × W × L) / 12. For several boards, multiply by the quantity. A 2×4 that is 8 ft long is (2 × 4 × 8) / 12 = 5.33 board feet.
What is a board foot?
A board foot is a unit of lumber volume equal to a board 1 inch thick, 12 inches wide and 12 inches long — 144 cubic inches. Any board of the same volume, such as a 1×12 one foot long, is one board foot.
Should I use the nominal or actual size for board feet?
Use the nominal size. A 2×4 is billed as a full 2 by 4 even though the dressed board is about 1½ × 3½ inches. This calculator uses the nominal size for board feet and the actual size for volume, so both figures are correct.
How many board feet are in a 2×4?
A 2×4 holds 0.667 board feet per foot of length. An 8-foot 2×4 is 5.33 board feet, and a 10-foot 2×4 is 6.67. The tool computes this for every common size.
How do hardwood quarters (4/4, 8/4) work?
Hardwood is sold in quarter-inch thicknesses: 4/4 is one inch, 5/4 is 1¼ inch, 8/4 is two inches, all measured rough (before surfacing). Board feet are billed on that rough thickness and the actual width you measure, because you pay for the sawn wood even after it is planed.
What's the difference between lineal feet and board feet?
Lineal (running) feet measure only length; board feet measure volume, factoring in thickness and width too. Ten 8-foot 2×4s are 80 lineal feet but 53.3 board feet. The calculator reports both.
Is a board foot the same as a cubic foot?
No. A board foot is 144 cubic inches; a cubic foot is 1,728 cubic inches, so one cubic foot equals 12 board feet. The tool shows volume in cubic feet or cubic metres alongside board feet.
Does it work in metric?
Yes. Switch units at the top and lengths, thicknesses and widths follow. Board feet are always shown as a US reference, with volume in cubic metres and lengths in metres for metric users.
Is the calculator private?
Yes. Every calculation runs in your browser. Nothing you enter is uploaded or stored on a server; your cut list is saved only in your own browser's local storage.
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