Board Foot Calculator

What is a board foot?

A board foot is the standard unit for buying hardwood lumber — it's a volume equal to a piece 12 inches square and 1 inch thick (144 cubic inches). Because boards come in all shapes, pricing by board foot lets a lumber yard charge fairly whether you buy a thick short plank or a thin long one.

The formula

Board feet = thickness(in) × width(in) × length(ft) ÷ 12. A 2″ × 6″ board that is 8 ft long is (2 × 6 × 8) ÷ 12 = 8 board feet. Multiply by quantity for the total, then by the price per board foot for your cost.

FAQ

Should I use nominal or actual dimensions?

Use the dimensions you're being charged for. Rough-sawn hardwood is usually sold at its full (actual) size, while softwood "2×4s" are charged at the nominal size even though they measure smaller. Ask your supplier which they quote, and enter that here.

What's the difference between a board foot and a linear foot?

A linear foot measures only length, ignoring thickness and width, while a board foot measures volume. Two boards that are each 8 feet long are the same in linear feet but very different in board feet if one is a 1×4 and the other a 2×12.

How do I handle a board measured in inches of length?

Convert the length to feet first by dividing inches by 12, then enter that value. For example, a 30-inch piece is 2.5 feet.

Why divide by 12 in the formula?

Thickness and width are in inches while length is in feet, so the raw product is in inch-by-inch-by-foot units. Dividing by 12 converts that into true board feet, since a board foot equals 144 cubic inches, or 12 inches square by 1 inch thick.

Is this calculator free, and does my data stay private?

Yes, it is free with no sign-up. All math runs in your browser, so the dimensions and prices you enter are never sent anywhere, and it works on mobile and desktop.