How do I calculate square footage of a room?

For a rectangular room: square footage = length (ft) x width (ft). Example: 12 ft x 15 ft = 180 sq ft. For irregular rooms, divide into rectangles, calculate each, and add together. For circular areas: sq ft = pi x radius squared.

How many square feet is a 10x12 room?

A 10 ft x 12 ft room = 120 square feet. For flooring or painting, add 10% for waste and cuts. So order approximately 132 sq ft of material.

How do I convert square feet to square meters?

Multiply square feet by 0.0929 to get square meters. Formula: sq meters = sq ft x 0.0929. Or divide by 10.764. Example: 500 sq ft = 46.45 sq meters. To go the other way: sq ft = sq meters x 10.764.

How many square feet is an acre?

1 acre = 43,560 square feet. An acre is roughly the size of a football field (without end zones). 1 square mile = 640 acres = 27,878,400 square feet. Common reference: a standard suburban lot is about 0.25 acres (10,890 sq ft).

Square Footage Calculator

Enter the length and width in your preferred unit to calculate the square footage (and other area units).

Square Footage Guide & Reference

Formula

Area (ft²) = Length (ft) × Width (ft)
For non-rectangular spaces, divide the area into rectangles, calculate each, and sum the results.

Worked example — Rectangular room

Room dimensions: 15 ft × 12 ft

Area = 15 × 12 = 180 ft²
In meters: 180 × 0.0929 = 16.72 m²

Worked example — L-shaped room

Split into two rectangles: 10×8 ft and 6×4 ft.

Rectangle 1 = 10 × 8 = 80 ft²
Rectangle 2 = 6 × 4 = 24 ft²
Total = 80 + 24 = 104 ft²

Conversion reference

From	To	Multiply by
1 ft²	in²	144
1 ft²	yd²	0.11111
1 ft²	m²	0.09290
1 m²	ft²	10.7639
1 acre	ft²	43,560
1 hectare	m²	10,000

Real-world uses

Flooring & tiling: Calculate material needed + add 10–15% for waste/cuts.
Painting: 1 gallon typically covers 350–400 ft² per coat.
Real estate: Property listings use ft² (US) or m² (international).
HVAC: 1 ton of cooling for every ~500–600 ft² (rule of thumb).

References

National Association of Realtors (NAR). Square Footage Measurement Guidelines.
ANSI Z765-2021. Calculating and Reporting Square Footage of Residential Buildings. American National Standards Institute.
NIST Handbook 44 — Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices.

Related Calculators

Calculating Square Footage for Common Projects

Square footage (sq ft) is the standard unit of floor area in the US. To calculate: multiply length (ft) × width (ft). For irregular rooms, divide into rectangles, calculate each, and sum the results. For triangular areas: ½ × base × height. For circular areas (e.g., round pools): π × radius². When planning flooring, paint, or tile, add 10–15% overage to account for cuts, waste, and future repairs. Measure each room at its widest points, including inside closets, for total floor area.

Square footage determines material quantities, rental rates, and property values. For flooring, divide the sq ft needed by the coverage of each box (usually listed on packaging) to find boxes needed. For paint, one gallon typically covers 350–400 sq ft per coat; interior rooms usually need two coats. For tile, measure sq ft, add 10% for breakage, and divide by tile size. Always draw a scaled sketch before purchasing materials to minimize costly errors.

Project Coverage Estimates

Material	Coverage	10% Overage Rule
Interior paint (1 gal)	350–400 sq ft	Add 10%
Vinyl flooring	Sold by sq ft	Add 10–15%
Hardwood flooring	Sold by sq ft	Add 15% (diagonal cuts)
Carpet	Sold by sq yd (9 sq ft)	Add 10%
Ceramic tile (12×12)	1 sq ft/tile	Add 10%