Board Foot Calculator

Hardwood is sold by volume, not by the stick. This converts your cut list into board feet and dollars before you’re standing at the sawmill doing phone math.

Lumber details

in
in
ft
$
Total board feet
Board feet per piece
Total cost
Hardwood thickness is quoted in quarters: 4/4 = 1 in, 5/4 = 1.25 in, 8/4 = 2 in — and it’s measured rough, before surfacing. A "4/4" board that planes to 13/16 still bills as a full inch.

What a board foot actually is

One board foot is a 1-inch-thick piece of wood, 12 inches wide and 12 inches long — 144 cubic inches. It's the universal unit for hardwood because boards come in random widths and lengths; volume is the only fair way to price them.

board feet = (thickness in × width in × length ft) ÷ 12

Worked example

Ten pieces of 4/4 red oak, 6 in wide and 8 ft long: (1 × 6 × 8) ÷ 12 = 4 bd ft each, 40 bd ft total — at $4.50/bd ft, a $180 lumber run. The same volume in 8/4 (2-in) stock is only five boards but the identical 40 bd ft and price, which is exactly the point of the unit.

Buying tips that save real money

Add 20–30% over your cut list for defects, grain matching and mistakes — hardwood always fights back. Know the quarters system, and remember thickness is measured rough: surfaced stock loses up to 1/4 in but bills at the rough size. FAS grade costs more but wastes less; #1 Common is the budget play when you can cut around knots.

Frequently asked questions

What does 4/4, 5/4, and 8/4 lumber mean?

It’s rough thickness in quarter inches: 4/4 is 1 inch, 5/4 is 1¼, 8/4 is 2 inches. After drying and surfacing, 4/4 typically finishes around 13/16 in — but you pay for the rough measurement.

Is a board foot the same as a linear foot?

No. A linear foot ignores width and thickness — fine for dimensional lumber like 2×4s sold by the stick. A board foot is volume, which is how hardwood and rough-sawn lumber are priced.

How much extra hardwood should I buy for a project?

20–30% over the cut list is the standard cushion. It covers checks, knots, snipe, grain-matching choices, and the one board you will absolutely cut wrong.

🧰 From the same shop: HouseMath — project calculators for the house and yard (mulch, paint, flooring, fence, pavers).