Calculate board feet of lumber instantly with our free online board foot calculator. Input nominal or actual dimensions to compute wood volume and estimate total cost.
Calculate board feet of lumber instantly with our free online board foot calculator. Input nominal or actual dimensions to compute wood volume and estimate total cost.
One board foot is a volume of wood equal to 144 cubic inches. You can also think of it as 1 ft² of surface at 1 inch thick, or 1/12 of a cubic foot.
Because most lumber is sold in “1×, 2×” sizes but planed to slightly smaller actual dimensions, many calculations use actual thickness and width.
A nominal 2×4 actually measures about 1.5 in × 3.5 in after drying and planing. For BF estimates, using actual sizes gives more realistic totals. This tool’s presets fill in typical dressed sizes.
Useful when estimating long runs (BF/ft = T × W ÷ 12).
| Size (actual) | BF per foot |
|---|---|
| 1×4 (0.75″ × 3.5″) | — |
| 1×6 (0.75″ × 5.5″) | — |
| 1×8 (0.75″ × 7.25″) | — |
| 2×4 (1.5″ × 3.5″) | — |
| 2×6 (1.5″ × 5.5″) | — |
| 2×8 (1.5″ × 7.25″) | — |
| 2×10 (1.5″ × 9.25″) | — |
| 2×12 (1.5″ × 11.25″) | — |
Calculate board feet in real-time as you type dimensions
Uses standard BF = (T × W × L) ÷ 12 calculation
Get instant price estimates for your lumber needs
A board foot (BF) is a volume measure for lumber equal to 144 in³ (12 in × 12 in × 1 in). The calculator uses the standard formula:
Values update as you type. Use the presets for common dressed sizes (e.g., 2×4 actual 1.5 in × 3.5 in).
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Understanding the mathematical foundation behind board foot calculations
BF = (T × W × L) ÷ 12
T = Thickness in inches
W = Width in inches
L = Length in feet
BF = Board Feet
One board foot equals 144 cubic inches (12″ × 12″ × 1″). When we multiply thickness (inches) × width (inches) × length (feet), we get a result in "inch²-feet". Dividing by 12 converts this to board feet, the standard unit for lumber volume.
Start with dimensions
2×4 board, 8 feet long
Actual: 1.5″ thick × 3.5″ wide × 8′ long
Multiply dimensions
1.5 × 3.5 × 8 = 42
Divide by 12
42 ÷ 12 = 3.5 BF
Result: 3.5 Board Feet
Common lumber calculations you'll encounter in projects
Material: 5/4 × 6 decking
Actual Size: 1″ × 5.5″
Length: 12 feet
Quantity: 50 boards
(1 × 5.5 × 12) ÷ 12 = 5.5 BF
Total: 275 BF
Material: 2×4 studs
Actual Size: 1.5″ × 3.5″
Length: 8 feet
Quantity: 100 studs
(1.5 × 3.5 × 8) ÷ 12 = 3.5 BF
Total: 350 BF
Material: 8/4 oak
Actual Size: 2″ × 8″
Length: 6 feet
Quantity: 8 boards
(2 × 8 × 6) ÷ 12 = 8 BF
Total: 64 BF
Quick reference for common lumber sizes and their board foot values per linear foot
| Nominal Size | Actual Size | BF per foot | BF per 8' | BF per 10' | BF per 12' |
|---|---|---|---|---|---|
| 1×4 | 0.75″ × 3.5″ | 0.219 | 1.75 | 2.19 | 2.63 |
| 1×6 | 0.75″ × 5.5″ | 0.344 | 2.75 | 3.44 | 4.13 |
| 1×8 | 0.75″ × 7.25″ | 0.453 | 3.63 | 4.53 | 5.44 |
| 2×4 | 1.5″ × 3.5″ | 0.438 | 3.50 | 4.38 | 5.25 |
| 2×6 | 1.5″ × 5.5″ | 0.688 | 5.50 | 6.88 | 8.25 |
| 2×8 | 1.5″ × 7.25″ | 0.906 | 7.25 | 9.06 | 10.88 |
| 2×10 | 1.5″ × 9.25″ | 1.156 | 9.25 | 11.56 | 13.88 |
| 2×12 | 1.5″ × 11.25″ | 1.406 | 11.25 | 14.06 | 16.88 |
Note: Values are based on actual (dressed) dimensions, not nominal sizes. Actual dimensions are slightly smaller due to planing and drying. Use these values for accurate material estimates.
Master the art of calculating board feet with our comprehensive guide
Most common method for lumber:
Example: (1.5 × 5.5 × 10) ÷ 12 = 6.875 BF Alternative method using inches:
Example: (1.5 × 5.5 × 120) ÷ 144 = 6.875 BF Quick calculation for long runs:
Example: (1.5 × 5.5) ÷ 12 = 0.6875 BF/ft
0.6875 × 10 ft = 6.875 BF