Lumber Calculator
Work out board feet, linear feet, volume and cost for a list of lumber, from nominal sizes like 2×4 and 2×10 or hardwood thicknesses like 4/4 and 8/4, with the actual dressed size of each.
How to Use
- Enter each size on its own line: nominal thickness and width in inches, length in feet, and how many.
- For hardwood sold by the quarter, enter the thickness in inches: 4/4 is 1, 5/4 is 1.25, 8/4 is 2.
- Enter a price per board foot, or per piece for each line if you buy by the stick.
- Read the board feet, the linear feet, the volume and the total cost.
Worked Example
A framing order: ten 2×4s 8 ft long and six 2×10s 16 ft long. One 2×4 × 8 ft = 2 × 4 × 8 ÷ 12 = 5.33 BF, so ten are 53.3 BF. One 2×10 × 16 ft = 2 × 10 × 16 ÷ 12 = 26.67 BF, so six are 160 BF. In all, 213.3 board feet and 80 + 96 = 176 linear feet.
The common mistake: using the actual size for softwood. 1.5 × 3.5 × 8 ÷ 12 = 3.5 BF for a 2×4, a third less than the 5.33 BF the yard charges for. Softwood is billed on nominal sizes.
Show Work
Formulas
Nominal and Actual Sizes
Lumber is named for the size it was sawn to while green. Drying shrinks it and planing smooths the faces, so a 2×4 leaves the mill at 1½ × 3½ in. The current sizes were set by the American Softwood Lumber Standard (PS 20) in the 1960s; older houses can have 2×4s that really are close to 2 in by 4 in, which matters when you repair or add to old framing.
Hardwood follows a different system. It is sold rough, by the board foot, with thickness in quarters of an inch (4/4, 5/4, 8/4) and random widths and lengths, and a buyer expects to lose around a quarter of the volume to planing and cutting out defects.
About This Calculator
This calculator adds up a cut list of up to four lumber sizes in board feet, linear feet and volume, shows each board’s actual dressed size, and prices the order per board foot or per piece. Lengths can be entered in feet or metres; thickness and width stay in nominal inches, as lumber is sold.
Everything runs in your browser; nothing is sent anywhere.
Related calculators: Framing Calculator, Deck Calculator, and Plywood Calculator.
Frequently Asked Questions
What is a board foot?
A volume of wood 1 in thick, 12 in wide and 12 in long: 144 in³, or 1/12 ft³. Board feet = thickness (in) × width (in) × length (ft) ÷ 12. A 2×4 that is 8 ft long is 2 × 4 × 8 ÷ 12 = 5.33 board feet.
Are board feet based on nominal or actual size?
Softwood dimension lumber is counted on its nominal size: a 2×4 is billed as 2 × 4 in even though it measures 1½ × 3½ in. Rough hardwood is counted on its rough thickness in quarters (4/4, 5/4, 8/4) and its actual width, measured before planing.
What are the actual sizes of 2×4, 2×6 and 2×10?
Dried and planed: 2×4 is 1½ × 3½ in, 2×6 is 1½ × 5½ in, 2×8 is 1½ × 7¼ in, 2×10 is 1½ × 9¼ in, 2×12 is 1½ × 11¼ in, and 1× boards are ¾ in thick. Up to 6 in nominal, the actual width is ½ in less; from 8 in up, ¾ in less.
How much is a board foot in metric?
One board foot is 2.36 litres, or 0.00236 m³; a cubic metre is 424 board feet. Timber in metric countries is usually sold by the cubic metre or by the linear metre of a given section.
What is the difference between board feet and linear feet?
Linear feet measure length only, whatever the size of the board: ten 8 ft boards are 80 linear feet. Board feet measure volume. Framing lumber is often priced per piece or per linear foot; hardwood almost always per board foot.
How do I use the Lumber Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Does it cost anything or need an account?
No. The tool is completely free, there is no account to create, and it keeps working offline after the page first loads.
Is anything I type uploaded?
No. The tool works entirely on your device, so the values you enter never leave your browser.
Common Use Cases
Framing order
10 × 2×4 × 8 ft = 53.3 BF and 6 × 2×10 × 16 ft = 160 BF: 213.3 BF in all.
Hardwood for a table
8/4 walnut, 6 in wide, four pieces 7 ft long: 28 BF; at $14/BF, $392.
Deck boards
29 boards of 5/4 × 6 in × 16 ft: 290 BF and 464 linear feet.
Timber beam
One 6×12 in beam 20 ft long: 120 BF, about 0.28 m³.
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