Linear × width = area
A linear foot is 12 inches of length, whatever the width. Multiply linear feet × width in inches ÷ 12 and you have square feet — the conversion for fence boards, decking, counter edging, baseboards and any product sold by length with a fixed width.
Why suppliers sell by the linear foot
Width varies by product, so length is the only comparable measure — a 6-inch fence board and a 12-inch one are both priced per foot of length. The calculator is bidirectional in practice: buyers convert linear feet to coverage, and coverage back to linear feet when the budget needs trimming.
Sources and standards
Where these figures come from
Every formula on this page is implemented from the published reference material below. Where a value depends on a regional code, the calculator lets you override it rather than assuming one jurisdiction.
- American Wood Council — span tables, lumber design values and the Wood Frame Construction Manual.
- APA — The Engineered Wood Association — panel span ratings and sheathing installation guidance.
Figures, formulas and reference tables last verified: 19 September 2026.