← Home & Construction Calculators
Calculate board feet for rough-sawn or dimensional lumber, including quantity, waste allowance, cubic volume and estimated cost.
Board-foot symbols
Board foot formulas
One board foot equals a volume of 144 cubic inches: a board 1 inch thick, 12 inches wide and 1 foot long.
Visual guide
Use actual dimensions when estimating the wood physically present. Use supplier tally dimensions when checking a purchase quote or invoice.
Worked example
Six boards measure 2 in × 8 in × 10 ft:
Six boards: 13.333 × 6 = 80 BF
With 10% waste: 80 × 1.10 = 88 BF
At $4.50 per board foot, material costs $396. Adding $50 delivery gives a project estimate of $446.
Metric example
A 50 mm × 200 mm × 3 m board is converted internally to inches and feet, producing approximately 12.71 board feet.
Board-foot conversions
| 1 board foot equals | Value |
|---|---|
| Cubic inches | 144 in³ |
| Cubic feet | 1/12 ft³ |
| Cubic meters | 0.00235974 m³ |
| Liters | 2.35974 L |
| 1,000 board feet | 2.35974 m³ |
Board feet measure volume. Linear feet measure only length, while square feet measure surface area.
Actual versus nominal lumber size
A nominal 2×4 is commonly smaller after drying and surfacing. Whether to use nominal or actual size depends on the purpose:
- Use actual dimensions for physical volume and finished projects.
- Use supplier tally dimensions to audit lumber pricing.
- For hardwood, thickness may be sold in quarter notation such as 4/4, 5/4 or 8/4.
- Confirm whether the seller prices rough, surfaced or net dimensions.
Measurement checklist
- Measure thickness and width at several points.
- Keep all dimensions in the selected system.
- Separate boards of different sizes.
- Add waste before calculating cost.
- Confirm whether the price is per BF, piece or thousand BF.
Frequently asked questions
What is one board foot?
It is 144 cubic inches of wood, such as 1 in × 12 in × 12 in.
How many board feet are in a 2×4×8?
Using nominal dimensions, 2 × 4 × 8 ÷ 12 equals 5.333 board feet.
Can I use metric dimensions?
Yes. The calculator converts millimeters and meters before applying the standard board-foot formula.
Why add waste?
Defects, end checks, knots, grain selection, cutting and joinery reduce usable yield.
Are board feet and square feet the same?
No. Board feet measure volume; square feet measure area.
Common mistakes
- Using length in inches with the feet-based formula.
- Confusing nominal and actual lumber dimensions.
- Omitting quantity or waste.
- Pricing adjusted BF but forgetting delivery.
- Combining different board sizes before calculating each group.