Calculators / Board foot
Board Foot Calculator
A board foot is 144 cubic inches of wood: 1 in thick, 12 in wide and 1 ft long. Board feet = thickness (in) × width (in) × length (ft) ÷ 12, so a 2x4 that is 8 ft long is 5.33 board feet. Enter your boards or logs below.
Calculate board feet
0.33 cu ft, 0.009 m³.
Board feet of lumber the log should yield under each rule. Buyers state which rule they use.
How much will it cost? Building a 12 × 16 ft raised wood deck with railing and stairs typically costs $15,340 with a contractor. Deck building cost in your state
How to calculate board feet
Lumber: thickness (in) × width (in) × length (ft) ÷ 12, times the number of boards. Example: ten 2x6 boards, 8 ft long: 2 × 6 × 8 ÷ 12 = 8 board feet each, 80 board feet in total. If you measure length in inches, divide thickness × width × length by 144 instead.
Logs: log rules estimate the lumber a log will yield. Purdue Extension gives the formulas, with D the small-end diameter inside the bark and L the length in feet: Doyle = (D - 4)² × L ÷ 16; Scribner = (0.79D² - 2D - 4) × L ÷ 16; the International 1/4 in rule uses a longer formula that allows for a 1/4 in saw cut (Purdue FNR-191).
Board feet in common lumber sizes
Nominal sizes, per piece.
| Size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1x4 | 2.67 | 3.33 | 4.00 | 5.33 |
| 1x6 | 4.00 | 5.00 | 6.00 | 8.00 |
| 1x8 | 5.33 | 6.67 | 8.00 | 10.67 |
| 1x12 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2x4 | 5.33 | 6.67 | 8.00 | 10.67 |
| 2x6 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2x8 | 10.67 | 13.33 | 16.00 | 21.33 |
| 2x10 | 13.33 | 16.67 | 20.00 | 26.67 |
| 2x12 | 16.00 | 20.00 | 24.00 | 32.00 |
| 4x4 | 10.67 | 13.33 | 16.00 | 21.33 |
| 4x6 | 16.00 | 20.00 | 24.00 | 32.00 |
| 6x6 | 24.00 | 30.00 | 36.00 | 48.00 |
Board feet in a 16 ft log
| Small-end diameter | Doyle | Scribner | International 1/4" |
|---|---|---|---|
| 10 in | 36 | 55 | 65 |
| 12 in | 64 | 86 | 97 |
| 14 in | 100 | 123 | 136 |
| 16 in | 144 | 166 | 181 |
| 18 in | 196 | 216 | 232 |
| 20 in | 256 | 272 | 290 |
| 24 in | 400 | 403 | 424 |
| 28 in | 576 | 559 | 584 |
Formula values. Published log tables round some entries and can differ by a few board feet.
Common questions
How many board feet is a 2x4x8?
2 × 4 × 8 ÷ 12 = 5.33 board feet, based on the nominal size. A 2x6x8 is 8 and a 2x12x16 is 32 board feet.
What does 20 board feet mean?
20 board feet is 20 × 144 = 2,880 cubic inches of wood. For example, 20 ft of 1x12 board, or 10 ft of 2x12.
How much area will 200 board feet cover?
Divide board feet by the thickness in inches: 200 board feet of 1 in (4/4) lumber covers about 200 sq ft, and 200 board feet of 2 in (8/4) lumber about 100 sq ft, before waste from milling and cutting.
Do I use nominal or actual size?
Lumber is priced on nominal size, so use that. A dry 2x4 actually measures 1.5 × 3.5 in, but it is sold as 2 × 4. Rough hardwood is sold in quarters of an inch: 4/4 is 1 in thick and 8/4 is 2 in, measured before planing.
Which log rule should I use?
Use the rule your buyer or mill uses: the rules are fair as long as everyone uses the same one. Doyle is the most widely used rule on private timber in the East and South, but it under-scales small logs and over-scales large ones. The International 1/4 in rule is probably the most accurate, and the best choice for estimating the lumber a log will actually yield (Purdue Extension).
How do I estimate lumber cost?
Multiply board feet by the price per board foot. Enter a price above and the calculator does it for you. Hardwood is usually priced per board foot, while construction lumber is usually priced per piece.
How we calculated this
Board feet use the standard definition (144 cubic inches). Log volumes use the Doyle, Scribner and International 1/4 in formulas published by Purdue Extension. We test the calculator against 305 worked examples, checked with a separate program. Sources.
Changelog
- : Published.
- : Formulas checked against 305 worked examples, verified with a separate program.
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