How do you calculate square footage?
Square footage is length × width, with both measured in feet — a 12 × 10 ft room is 120 sq ft. For odd shapes, split them into rectangles and add the pieces. Handy conversions: 1 square yard = 9 sq ft, 1 acre = 43,560 sq ft, and 1 square metre ≈ 10.76 sq ft.
Source: Area geometry (exact conversions) · Verify against your AHJ and the adopted code edition.
Square footage is simply length × width, with both measured in feet. A room 12 ft by 10 ft is 120 square feet.
Two things trip people up:
- Odd shapes. Break an L-shaped or irregular room into rectangles, find each one’s area, and add them up. Subtract cut-outs the same way.
- Mixed units. Convert to feet first — inches ÷ 12 — before multiplying, so a measurement of 10 ft 6 in becomes 10.5 ft.
Useful conversions once you have the square footage:
- 1 square yard = 9 sq ft (flooring is often priced by the square yard).
- 1 acre = 43,560 sq ft (land).
- 1 square metre ≈ 10.76 sq ft (metric plans).
For materials, add a waste allowance on top of the bare area — the amount depends on the product and the cut pattern.
Work it out: the square footage calculator gives the area in sq ft, sq yd, m², and acres — and an optional material cost — from a length and width.