Calculate board feet (FBM) for lumber orders. Enter quantity, thickness, width, and length
to get the total volume and estimated cost.
Lumber Cut List
Size mode
Order Summary
Base board feet0.00 bd ft
Added waste0.00 bd ft
Order board feet0.00 bd ft
MBF equivalent0.000 MBF
Cubic feet0.00 ft³
Weighted price / bd ft$0.00
Estimated cost$0.00
Each row uses thickness in inches × width in inches × length in feet ÷ 12, then multiplies by quantity.
Board foot formula and size guidance
Formula
(thickness in × width in × length ft) ÷ 12 × quantity
Use 144 instead of 12 when all three dimensions are in inches.
Nominal vs. actual
Nominal lumber is the named size, such as 2×4. Actual dressed lumber is smaller, often 1.5" × 3.5" for a 2×4. Use actual size for pricing and precise volume.
Quarter thickness
Hardwood quarters describe rough thickness: 4/4 is about 1", 5/4 is about 1.25", 6/4 is about 1.5", and 8/4 is about 2" before surfacing.
Ordering note: add 5% to 10% waste for straightforward cut lists and 10% to 15% for defects, matching grain, complex trim, or rough stock that will be milled.
Worked examples
2x4x8 framing board
(1.5 × 3.5 × 8) ÷ 12 = 3.50 bd ft
Ten 2x4x8 boards equal 35.00 board feet before waste.
Hardwood 5/4 board
(1.25 × 6 × 8) ÷ 12 = 5.00 bd ft
Four 5/4 × 6" × 8' boards equal 20.00 board feet before waste.
Mixed order with cost
35 bd ft + 20 bd ft = 55 bd ft; 10% waste = 60.5 bd ft
At $6.50 per board foot, the estimated order cost is $393.25.
Common board feet chart
Chart values use common actual dressed dimensions for 1x and 2x lumber. Quarter-size rows use rough thickness.
Size
Per linear ft
8 ft
10 ft
12 ft
16 ft
Methodology
The calculator converts every row to the standard board foot formula: thickness in inches × width in inches × length in feet ÷ 12. Metric dimensions are converted before the formula runs. Costs are estimated from row price per board foot multiplied by base board feet, then increased by the selected waste factor.
Results are rounded to two decimals for board feet and cubic feet, three decimals for MBF, and cents for cost. Last updated: July 5, 2026. Editorial review: Starlight Tools construction calculator team, using standard lumber-yard board foot practice.
Board feet FAQ
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet, divide by 12, then multiply by quantity.
How many board feet are in a 2x4x8?
Using actual dressed dimensions, a 2x4x8 is about 3.5 board feet: 1.5 × 3.5 × 8 ÷ 12.
Should I use nominal or actual dimensions?
Use actual dimensions for precise volume and cost. Nominal size is useful for identifying lumber, but it usually overstates finished dimensions.
What is the difference between board foot and linear foot?
A board foot measures volume. A linear foot measures only length, so it does not include thickness or width.
How do I calculate board feet when length is in inches?
Use thickness × width × length in inches ÷ 144, or convert the length to feet and divide by 12.
What does 4/4 or 5/4 lumber mean?
Quarter sizes name rough hardwood thickness. 4/4 is about 1" rough and 5/4 is about 1.25" rough before surfacing.
How do I convert board feet to MBF?
Divide board feet by 1,000. For example, 250 board feet equals 0.25 MBF.
How much extra lumber should I buy for waste?
Use 5% to 10% for simple cuts and 10% to 15% or more for defects, matching, milling, or complex layouts.
