Board Foot Calculator
Enter each board's thickness, width, length and quantity to add up board feet and the cost of your lumber. Works with nominal or actual sizes, feet or inches, and metric dimensions.
| Description | Thickness (in) | Width (in) | Length (ft) | Qty | Board feet | Cost | Remove |
|---|
1 board foot = 144 cubic inches (12 × 12 × 1 in). Prices vary by species, grade and supplier – this is an estimate.
How to use the Board Foot Calculator
- Choose units: inches and feet, or millimeters and meters.
- Add your boards with Quick add, or type thickness, width, length and quantity in the table.
- Pick nominal or actual size and whether lengths are in feet or inches.
- Enter the price per board foot and an optional waste allowance.
- Press Calculate board feet to see the totals, then copy the cut list or download a CSV.
Board foot formula
A board foot is a volume of wood 12 in × 12 in × 1 in, or 144 cubic inches.
- Board feet = thickness (in) × width (in) × length (in) ÷ 144
- With length in feet = thickness (in) × width (in) × length (ft) ÷ 12
- Metric = thickness (mm) × width (mm) × length (m) ÷ 1,000,000 ÷ 0.0023597 m³
- Cost = board feet × price per board foot
Worked example: ten 2×6 boards 8 ft long = 2 × 6 × 8 ÷ 12 × 10 = 80 BF, plus four 1×8 boards 10 ft long = 1 × 8 × 10 ÷ 12 × 4 = 26.67 BF. Total 106.67 BF; at $3.50 per board foot that is $373.33.
Board feet per piece for common lumber
| Nominal | Actual size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|---|
| 1×6 | ¾ × 5½ in | 4.00 | 5.00 | 6.00 | 8.00 |
| 2×4 | 1½ × 3½ in | 5.33 | 6.67 | 8.00 | 10.67 |
| 2×6 | 1½ × 5½ in | 8.00 | 10.00 | 12.00 | 16.00 |
| 2×8 | 1½ × 7¼ in | 10.67 | 13.33 | 16.00 | 21.33 |
| 2×10 | 1½ × 9¼ in | 13.33 | 16.67 | 20.00 | 26.67 |
| 2×12 | 1½ × 11¼ in | 16.00 | 20.00 | 24.00 | 32.00 |
| 4×4 | 3½ × 3½ in | 10.67 | 13.33 | 16.00 | 21.33 |
| 6×6 | 5½ × 5½ in | 24.00 | 30.00 | 36.00 | 48.00 |
Values use nominal dimensions, which is how board feet are normally counted for pricing.
Nominal vs. actual lumber sizes
Dimensional lumber is named by its rough-sawn size; drying and planing make it smaller. The calculator's actual-size mode uses these standard rules:
| Nominal dimension | Actual (dressed) |
|---|---|
| 1 in | ¾ in |
| 1¼ in (5/4) | 1 in |
| 1½ in (6/4) | 1¼ in |
| 2 to 7 in | ½ in less (2 → 1½, 4 → 3½, 6 → 5½) |
| 8 in and up | ¾ in less (8 → 7¼, 10 → 9¼, 12 → 11¼) |
Rough hardwood is usually sold by the board foot at its rough thickness (4/4, 5/4, 8/4), while home-center boards are often priced per piece or per linear foot.
Frequently asked questions
How do you calculate board feet?
Multiply thickness (in) × width (in) × length (in) and divide by 144. With the length in feet, use thickness × width × length ÷ 12. A 2×6 that is 8 ft long is 2 × 6 × 8 ÷ 12 = 8 board feet.
How many board feet are in a 2×4×8?
Using nominal size a 2×4×8 is 2 × 4 × 8 ÷ 12 = 5.33 board feet. Its actual dressed size is 1.5 × 3.5 in, which is only 3.5 board feet of real wood.
Should I use nominal or actual dimensions?
Lumber yards price softwood and rough hardwood by nominal size, so use nominal for cost. Use actual dressed size when you need the true volume of wood, for example to estimate weight.
What do 4/4, 5/4 and 8/4 mean?
Hardwood thickness is sold in quarters of an inch: 4/4 is 1 in, 5/4 is 1¼ in, 6/4 is 1½ in and 8/4 is 2 in thick, measured rough before planing.
How do I convert board feet to cubic meters?
One board foot is 144 cubic inches, or 0.00236 m³. So 1 m³ is about 423.8 board feet, and 1 cubic foot equals 12 board feet.
How much waste should I add?
Add 10–15% for straight cuts in good stock and 20–30% for rough hardwood with defects, or when you need matching grain.