Board Foot Calculator

Total up to 12 lumber sizes in board feet with mixed metric or imperial dimensions, piece counts and an optional allowance.

Total a mixed lumber list

Enter each board size and its piece count. Mix inches, feet and metric units in the same estimate.

Starter example. Edit the fields to calculate with your own numbers.

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Total board feet for mixed lumber sizes and quantities, with independent units and an optional extra-volume allowance.

How to use it

1Enter thickness, width, length and pieces.
2Set the unit for each dimension and add other sizes as needed.
3Optionally enter an allowance and calculate.
4Review row totals and export CSV or JSON.

Example

Input: Three 1 in × 6 in × 8 ft boards with a 10% allowance
Output: 12 board feet before the allowance and 13.2 including it.

What happens to your data

Measurements and generated downloads stay in this browser tab until you save or share them. Anonymous workflow records exclude entered dimensions and quantities.

Last updated November 2026

Calculate board feet for rectangular lumber. Enter each size once with its piece count, choose units for thickness, width and length, and see a per-row breakdown. Add an optional extra-volume allowance to the subtotal and export the tally.

How it works

One board foot equals 144 cubic inches. Convert each dimension to inches, multiply the thickness, width and length, then divide by 144. Multiply by the row’s piece count and add the row totals. If you enter an allowance, the calculator adds that percentage of the subtotal as extra volume. It does not round that allowance into whole boards or optimize a cut list.

Each dimension can use inches, feet, millimetres, centimetres or metres. Metric conversions use the exact relationship of 25.4 mm per inch. Decimal and fractional inputs are kept exact through the calculation. On-screen totals are rounded for readability, and the exports retain the exact total numerator and denominator.

Use 1–12 sizes, 1–9,999 pieces per size and a 0–100% optional allowance. The tool calculates from the dimensions you enter. Choose measured sizes for physical volume and use your supplier’s stated measurement basis if you need to compare with their tally. Actual and nominal dimensions can differ.

Worked example: Total three boards with an optional allowance

Input: Three boards, each 1 inch thick, 6 inches wide and 8 feet long, with 10% extra.
Result: 4 board feet per board, 12 before allowance and 13.2 with the allowance.

Common use cases

Total a lumber list with several sizes and piece counts.
Combine imperial dimensions with metric measurements in one takeoff.
Compare the measured subtotal with an optional extra-volume allowance.
Save a row-by-row CSV or exact JSON tally.

Frequently asked questions

What is a board foot?＋

It is a volume of 144 cubic inches, equivalent to a board 1 inch thick, 12 inches wide and 12 inches long.

Can I mix inches and metric units?＋

Yes. Set the unit beside each dimension. The calculator converts it to inches before calculating the volume.

Should I enter nominal or actual dimensions?＋

Enter measured dimensions for physical volume. If you are comparing with a supplier tally, use the dimensions and measurement basis specified by that supplier.

Does adding 10% tell me how many more boards to buy?＋

The allowance adds 10% to the volume. The number and sizes of extra pieces depend on the planned cuts and available boards.