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Board Foot Calculator

Board feet and cost for hardwood, lumber and dimensional stock, in any thickness, width and length.

in
in
ft
pieces
USD

Results update as you type. The maths runs entirely in your browser — nothing you type is sent anywhere.

Before you order: get three written quotes on identical scope. The spread between the cheapest and dearest bid on the same job is routinely 30%, and it costs nothing to ask.

Board feet are the units hardwood dealers actually use, and the formula is simple: thickness in inches, times width in inches, times length in feet, divided by twelve. What trips people up is that the number describes nominal dimensions, not the planed board you carry out of the yard.

A rough-sawn 8/4 board is two inches thick. Once it is planed flat and jointed, expect to lose a quarter inch or more. Buying board feet is buying the raw volume, not the finished dimension — plan your cutting list against the finished size, and leave extra for the waste that flattening always takes.

How this calculator works

Every field is editable and the result updates as you type — nothing is submitted anywhere, all the maths runs in your browser. That matters for a number you are about to spend money on: you can see exactly which input moved the answer, and by how much.

What this calculation assumes

Assumes nominal dimensions and straight, defect-free stock. Hardwood grading allows a percentage of defects that you still pay for, and planing a rough board flat removes a quarter inch or more before it becomes usable.

Treat the result as an order-of-magnitude check rather than a final quantity. Product packaging changes, regional labour rates vary by a factor of two, and no calculator has seen your actual site.

Frequently asked questions

What exactly is a board foot?

One square foot of one-inch-thick lumber: 144 cubic inches. A board 1 inch thick, 12 inches wide and 12 inches long is one board foot. Thicker stock counts proportionally, so a 2 inch thick board of the same face area is two board feet.

Why is a 2x4 not two inches by four inches?

Because it is planed down from a rough 2x4 to a finished 1.5 by 3.5 inches. Construction lumber is still sold and priced by its nominal size, so a 2x4 stud is billed as two-by-four even though it measures smaller. Hardwood is different: it is sold by true thickness in quarters.

How much extra lumber should I buy?

Ten percent for a simple project with straight cuts, fifteen to twenty for anything with mitres, angled cuts or figure that has to be matched across a glue-up. For hardwood, add more if you are ordering sight-unseen, because defect allowance is part of the grading system.

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