Board Foot Calculator
Build your cut list and get the board feet for your whole project. Buying dressed S4S means it arrives ready to use; buying rough means surfacing it yourself — switch modes to see exactly how much each takes.
Add at least one part to see your board feet.
How the board foot calculator works
A board foot is 144 cubic inches — thickness × width × length in inches, divided by 144. For a real project you add up every part, which is what the cut list above does. Then a waste buffer covers offcuts, trimming and the occasional mistake. For the full method see our board foot guide.
Dressed (S4S) vs rough
Dressed lumber is surfaced four sides and arrives flat, square and at a finished size — for us that's 3/4″ and 1-3/4″ — so the board feet you buy are the board feet you use. Rough lumber is oversized: a 4/4 board (about 1″ rough) finishes near 3/4″, and 8/4 (about 2″) finishes near 1-3/4″. In rough mode the calculator steps your finished thickness up to the right rough size and adds width and length for jointing and trimming, so you can see how much extra you'd buy — and that you'll need a jointer and planer. More on that in S4S vs. rough lumber.
How do you calculate board feet?
Thickness × width × length in inches, divided by 144, for each part — then add the parts together. The calculator does this and adds your waste buffer.
Why does rough lumber need more board feet?
You buy it oversized and plane away material to reach your finished size, so the same finished part starts from a larger rough board.
Does 4/4 finish at a full inch?
No — 4/4 is about 1″ in the rough and usually finishes near 3/4″. 8/4 finishes near 1-3/4″.
Do I need machines for rough lumber?
Yes — typically a jointer and a thickness planer to flatten and dimension it. Dressed S4S skips that step entirely.
Estimates only. Real boards vary in width and length and rough stock contains defects, so always confirm against your actual material and keep a buffer.
