Masukkan dimensi — keputusan dikemas kini serta-merta. Guna BF = (T in × W in × L ft) ÷ 12.
Masukkan dimensi — keputusan dikemas kini serta-merta. Guna BF = (T in × W in × L ft) ÷ 12.
Satu board foot ialah isipadu kayu bersamaan 144 inci padu. Ia juga boleh dianggap sebagai 1 ft² permukaan setebal 1 inci, atau 1/12 kaki padu.
Kerana kebanyakan kayu dijual dalam saiz “1×, 2×” nominal tetapi diratakan kepada dimensi sebenar yang sedikit lebih kecil, banyak pengiraan menggunakan ketebalan dan lebar sebenar.
2×4 nominal sebenarnya berukuran kira-kira 1.5 in × 3.5 in selepas pengeringan dan perataan. Untuk anggaran BF, menggunakan saiz sebenar memberi jumlah yang lebih realistik. Pratetap alat ini mengisi saiz siap yang biasa.
Berguna untuk menganggar panjang yang panjang (BF/ft = T × W ÷ 12).
| Saiz (sebenar) | BF per kaki |
|---|---|
| 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
Board foot (BF) ialah ukuran isipadu kayu bersamaan 144 in³ (12 in × 12 in × 1 in). Kalkulator menggunakan formula standard:
Nilai dikemas kini semasa anda menaip. Gunakan pratetap untuk saiz siap biasa (cth., 2×4 sebenar 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