Board Foot Calculator for Lumber Buying
Enter thickness, width, length, and quantity to get board feet. Add your supplier's $/BF for cost, then choose a waste allowance only if your project needs one.
Board dimensions
Choose each unit separatelyTotal Board Feet
Per Board
4 BF
(1 in × 6 in × 96 in × 1) ÷ 144 = 4 BF
Purchase planning allowance (optional)
Waste depends on your cut list, defects, grain, and board selection. Choose only what fits your project.
Rough hardwood thickness
These presets change thickness only. Your width stays unchanged.
2× dimensional lumber
Choose nominal or actual before applying a size.
Your board dimensions
Thickness is the thin edge, width runs across the face, and length runs along the board.
- Thickness: 1 in
- Width: 6 in
- Length: 8 ft
Why the lumberyard tally may differ
Some hardwood is tallied at a standard thickness or from measurements taken before surfacing. Planing removes material, so a finished board can measure smaller than the size used for billing.
Rough or standard billed size A yard may tally from a standard thickness or a measurement taken before surfacing. Example billed reference: 4/4 (1 in standard thickness).
Surfaced or finished size Your tape measures the board after material has been removed. Example finished measurement after surfacing: 13/16 in.
Which dimensions should you enter?
Use the numbers that match the question you are answering. This calculator uses every dimension exactly as entered and makes no hidden conversion.
- Rough dimensions
- Measurements before the board is planed or jointed.
- Nominal dimensions
- A named trade size, such as 2×4, rather than the board's measured size.
- Actual dimensions
- The thickness, width, and length you physically measure.
- Surfaced dimensions
- Finished measurements after one or more faces have been planed.
Supplier rules vary. Confirm the invoice measurement practice with your supplier. This calculator reports the physical volume of the dimensions you enter; it does not reproduce NHLA commercial rounding, supplier-specific tally rules, decide whether a quote is fair, or resolve invoice disputes.
Method reviewed: July 20, 2026NHLA Rules for the Measurement and Inspection of Hardwood and Cypress
Calculation method
Board foot formula and buying example
A board foot is 144 cubic inches. The calculator converts every dimension to inches, calculates raw lumber volume, and keeps any planning allowance separate.
BF = thickness (in) × width (in) × length (in) × quantity ÷ 144
BF = thickness (in) × width (in) × length (ft) × quantity ÷ 12
Example: five 4/4 × 6 in × 8 ft boards
(1 × 6 × 8 × 5) ÷ 12 = 20 BF. At a supplier quote of $8/BF, the raw cost is $160. A 15% planning allowance makes the purchase target 23 BF and $184, while raw volume stays 20 BF.
Board feet measure volume, not cut-list yield. Board lengths, defects, grain, and part layout can still make an order too small for a project.
Your supplier may tally rough lumber at standard thickness or before surfacing, and may apply commercial measurement rules that this calculator does not reproduce. Confirm the dimensions and tally method on the quote or invoice. The calculator's dimension guide above records the NHLA method source and review date.
How to use the board foot calculator
- 1
Enter the board dimensions
Enter thickness, width, length, and quantity. Choose rough, nominal, actual, or surfaced dimensions to match the decision you are making.
- 2
Read raw board feet
Use Total Board Feet as the physical volume of the measurements you entered. The live formula shows the same calculation with your values.
- 3
Add the supplier quote if you have one
Enter the quoted price per BF to calculate raw cost. Leave it blank when you do not have a quote.
- 4
Choose a planning allowance if needed
Add waste only for your project needs. Raw BF stays visible while Purchase Target BF includes the allowance.
Continue with a specific lumber task
The homepage handles the broad board-foot calculation. Use these maintained pages when your next job is cost planning, conversion, log scaling, or learning the method.
Cost
Conversions
- Board feet to linear feetConvert a lumber volume to length for a known thickness and width.
- Linear feet to board feetTurn a known run of lumber into board feet.
- Board feet to square feetEstimate coverage area from BF and thickness.
- Square feet to board feetConvert a known area and thickness into lumber volume.
Logs and guides
Frequently Asked Questions
Multiply thickness × width × length (all in inches), then divide by 144. For a 2×6×96 inch board: (2 × 6 × 96) ÷ 144 = 8 board feet. If length is in feet, divide by 12 instead of 144.