Board-foot calculator

What is a board foot?

A board foot is a unit of lumber volume equal to 144 cubic inches, the same amount of wood as a piece that is 1″ thick × 12″ wide × 12″ long. It’s how lumber yards price wood in bulk, so calculating your board feet before you visit the yard prevents under-buying and over-spending.

Rough vs. surfaced dimensions

Lumber is sold by its rough (nominal) dimensions, the size before it was milled flat. A “1-inch” board actually measures about ¾″ after surfacing; a “2×4” is really 1½″ × 3½″. Always use rough dimensions when estimating board feet so your count matches what the yard charges you.

How to measure a rough board

1. Thickness, measure across the thinnest face in inches. Round up to the nearest standard thickness (¾″, 1″, 1¼″, 1½″, 2″).
2. Width, measure the widest face. For a waney-edge (live edge) board, measure at the widest point and expect some waste.
3. Length, measure in inches end to end.
4. Add a 10–15% waste allowance to your total for jointing, planing, and cut-offs. First-time buyers typically need 20%.

Tip for beginners

If you’re not sure which species to buy, check the species reference and filter by Beginner-friendly. Poplar and soft maple are forgiving, inexpensive, and available at most hardwood dealers.