KerfCalc

Board Foot Calculator

Board feet for a whole cutting list, not just one board. Enter your sizes, add a realistic waste allowance, and you get the volume, the cost, and what to actually ask for at the yard.

Units

Notes

What is a board foot?

One board foot is 144 cubic inches — a piece 12 in × 12 in × 1 in. It is a volume, not an area, so a thicker board of the same face size costs more.

Why the waste allowance matters

Rough lumber is not the size on the tag. Between planing, jointing, defects and end checks, 15-25% is normal for rough stock and 10% for surfaced boards. Buying the exact number always comes up short.

Quarters explained

4/4 is one inch, 8/4 is two inches, 12/4 is three. It refers to rough thickness before surfacing, so 4/4 dressed usually lands around 3/4 in.

What this does not do

It does not grade lumber or account for the specific defect pattern of your boards. Sight every board at the yard.