Square Footage Calculator

Add up to three rectangles, triangles, circles or trapezoids, subtract a cut-out, and get total square feet and square meters with an optional cost.

Interactive calculator · Method SQUARE-FOOTAGE-1.0 · Last reviewed: 2026-11-04

Calculate your scenario

Rectangle = A × B; triangle = A × B ÷ 2 (B is the perpendicular height); circle = π × A² ÷ 4 (A is the diameter); trapezoid = (A + B) ÷ 2 × C.

Your inputs

Try an example

Measurement unit

Area 1 shape

Area 1 dimension A (ft or m)

Area 1 dimension B (ft or m)

Area 1 dimension C (trapezoid height) (ft or m)

Area 2 shape

Area 2 dimension A (ft or m)

Area 2 dimension B (ft or m)

Area 2 dimension C (trapezoid height) (ft or m)

Area 3 shape

Area 3 dimension A (ft or m)

Area 3 dimension B (ft or m)

Area 3 dimension C (trapezoid height) (ft or m)

Cut-out length (rectangle to subtract) (ft or m)

Cut-out width (ft or m)

Price basis

Price (example $4.50; 0 to skip) ($ per sq ft or m²)

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Total area 140 sq ft

Total area in square meters 13.01 m²

Areas before cut-out 140 sq ft

Cut-out 0 sq ft

Estimated cost $630.00

140 sq ft − 0 sq ft = 140 sq ft (13.01 m²) × $4.50/sq ft = $630.00.

How to use the calculator

Split the space into up to three simple shapes, pick each shape and enter its dimensions in feet or meters, add a rectangle to subtract (an island or stair opening), then enter a price if you want a cost.

What the result means

A 12 × 10 ft room with a 5 × 4 ft alcove is 140 sq ft (13.01 m²); at an example $4.50 per sq ft that is $630.

Formula and units

Rectangle = A × B; triangle = A × B ÷ 2 (B is the perpendicular height); circle = π × A² ÷ 4 (A is the diameter); trapezoid = (A + B) ÷ 2 × C. The areas are added, the cut-out rectangle is subtracted, and the total is shown in square feet and square meters (1 sq ft = 0.09290304 m²). Cost = area × the price you enter.

Worked examples

12 × 10 ft room with a 5 × 4 ft alcove: Area 1 dimension A: 12 ft or m; Area 1 dimension B: 10 ft or m; Area 1 dimension C (trapezoid height): 0 ft or m; Area 2 dimension A: 5 ft or m; Area 2 dimension B: 4 ft or m; Area 2 dimension C (trapezoid height): 0 ft or m; Area 3 dimension A: 0 ft or m; Area 3 dimension B: 0 ft or m; Area 3 dimension C (trapezoid height): 0 ft or m; Cut-out length (rectangle to subtract): 0 ft or m; Cut-out width: 0 ft or m; Price (example $4.50; 0 to skip): 4.5 $ per sq ft or m²; Measurement unit: ft; Area 1 shape: rect; Area 2 shape: rect; Area 3 shape: none; Price basis: sqft.
Example result: Total area: 140 sq ft; Total area in square meters: 13.01 m²; Areas before cut-out: 140 sq ft; Cut-out: 0 sq ft; Estimated cost: $630.00.

Metric garden: circle, trapezoid and triangle beds: Area 1 dimension A: 4 ft or m; Area 1 dimension B: 10 ft or m; Area 1 dimension C (trapezoid height): 0 ft or m; Area 2 dimension A: 6 ft or m; Area 2 dimension B: 4 ft or m; Area 2 dimension C (trapezoid height): 3 ft or m; Area 3 dimension A: 3 ft or m; Area 3 dimension B: 2 ft or m; Area 3 dimension C (trapezoid height): 0 ft or m; Cut-out length (rectangle to subtract): 1 ft or m; Cut-out width: 1 ft or m; Price (example $4.50; 0 to skip): 20 $ per sq ft or m²; Measurement unit: m; Area 1 shape: circle; Area 2 shape: trap; Area 3 shape: tri; Price basis: sqm.
Example result: Total area: 318.25 sq ft; Total area in square meters: 29.57 m²; Areas before cut-out: 30.57 m²; Cut-out: 1 m²; Estimated cost: $591.33.

Limitations and common mistakes

For rooms, gardens, decks and similar flat areas measured with a tape. It is not a land survey, legal lot area or map measurement, and it does not include slopes, waste or overage for materials. The price is your own quote.

Using the slanted side of a triangle or trapezoid instead of the perpendicular height, which overstates the area.

Sources and assumptions

Method SQUARE-FOOTAGE-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.