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Lumber Calculator

A lumber calculator totals the board feet, linear feet and cost for a quantity of boards of a given size — the figures you need to price a lumber order or compare boards sold by the board foot. Enter the nominal size, the length and how many, and it adds them up.

Your measurements

Result

Board feet trip people up because they use the nominal size (a 2×4 is figured as 2×4, not its actual 1.5×3.5). This uses the nominal dimensions, the way lumberyards price it, so your estimate matches the quote.

How it is calculated

Board feet per board = (nominal thickness in × nominal width in × length ft) ÷ 12. Total = that × the number of boards. One board foot is 144 cubic inches. Lumber is priced by the board foot using nominal sizes, so cost = total board feet × your price per board foot.

Steps

Enter the nominal thickness and width (e.g. 2 and 6 for a 2×6).
Enter the length of each board and how many boards.
Read the total board feet and linear feet.
Add a price per board foot for a cost estimate.
Use board feet to compare prices across different board sizes.

Worked example

Ten 2×6 boards at 8 ft each is 80 board feet (8 bf each) and 80 linear feet; at $3/bf that's about $240.

Common questions

What is a board foot?

A volume of lumber equal to a 1-inch-thick, 12-inch-wide board one foot long — 144 cubic inches. Lumber is priced by the board foot.

How do I calculate board feet?

Nominal thickness × width (inches) × length (feet) ÷ 12, then multiply by the number of boards. The calculator does it.

Nominal or actual size?

Nominal — a 2×4 is figured as 2×4 even though it measures 1.5×3.5 in. That's how board feet and pricing work.

How do I compare lumber prices?

Convert everything to price per board foot. Then a 2×6 and a 2×8 can be compared fairly regardless of length.