Lumber Calculators
Lumber is priced in board feet and sold in pieces. Two languages for the same pile of wood. These calculators translate between them and count the studs, boards and stringers your project really takes.
Board Foot Calculator
Board feet from lumber dimensions, plus cost.
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Stud Framing Calculator
Studs and plates for a framed wall.
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Stair Calculator
Steps, rise, run and stringer length.
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Board feet, nominal sizes, and honest counts
Hardwood and rough lumber are priced by the board foot, a volume of wood 12 in wide × 12 in long × 1 in thick. The Board Foot Calculator converts any board's dimensions and piece count into board feet and cost at your yard's rate. One catch runs through all lumber maths: sizes are nominal. The 2×4 you buy is really 1.5 × 3.5 in, and a 2×6 is 1.5 × 5.5 in. Plan projects on actual sizes, and know that board-foot pricing at hardwood yards is usually figured on the nominal size.
Framing counts are spacing geometry plus allowances. At 16 in on-center, a wall needs 0.75 studs per linear foot, plus one to close the run. Then corners, intersections and openings add more, and the plates run three times the wall length. The stud calculator counts all of it, because the spacing-only number is always the floor, never the order.
Stairs are the one lumber project governed by hard numbers. The residential code caps riser height at 7-3/4 in and requires at least 10 in of tread, with every riser in a flight equal. The Stair Calculator divides your total rise into equal, code-legal risers, pairs them with treads by the classic comfort rule (2 × riser + tread = 25 in), and gives the stringer length to buy.
Frequently asked questions
What is a board foot?
A unit of lumber volume: a board 12 in × 12 in × 1 in thick, or 144 cubic inches. Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. A 2×4×8 is 5.33 board feet on its nominal size.
Why is a 2×4 not 2 by 4 inches?
The name is the rough-sawn size from the mill's history; after drying and planing, a modern 2×4 measures 1.5 × 3.5 in. Always design and measure with the actual dimensions. Every calculator here uses them.
How many studs do I need per foot of wall?
At 16 in on-center spacing, 0.75 studs per linear foot plus one per run, before the extra studs that corners, intersections and openings need. At 24 in spacing it's 0.5 per foot; at 12 in, one per foot.