TrowelMath

Square footage calculator

  • ENERGY STAR sizing · manufacturer bag yields
  • Updated Oct 23, 2026
  • Runs in your browser
  • Methodology
  • Instant answers. Results update as you type, with a visual breakdown.
  • Share or print. Copy a link with your numbers, or print a clean summary.
  • Sourced and private. ENERGY STAR sizing · manufacturer bag yields. Nothing you enter leaves your device.

Split L-shaped rooms into rectangles and add them.

Formulas for common shapes

Rectangle: length × width. Triangle: ½ × base × height. Circle: π × radius². For an L-shaped or irregular room, split it into rectangles, work out each one and add them.

Worked example

A 12 × 15 ft living room is 180 sq ft. Add an attached 5 × 6 ft alcove (30 sq ft) for 210 sq ft. To convert to square yards, divide by 9 (23.3 sq yd); to square metres, multiply by 0.0929 (19.5 m²).

Frequently asked questions

How do I find square feet?

Length × width in feet.

How do I measure in feet and inches?

Convert inches to feet first: 12 ft 6 in = 12.5 ft.

Does this include waste?

No. Add waste in the material calculators.