Square Footage Calculator

Shape

Length (ft) Width (ft)

Cost per sq ft — optional, to estimate total cost

Area —

Square yards —

Acres —

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Free square footage calculator for rectangles, circles, and triangles — get the area in square feet, square yards, and acres, plus a total cost estimate if you know the price per square foot.

How it works

Choose a shape: rectangle, circle, or triangle
Enter the dimensions
See the area in square feet, square yards, and acres — and total cost if you enter a price per square foot

Frequently asked questions

How do I calculate the square footage of a circle?

Enter the diameter — this calculator converts it to a radius and applies the standard area formula (π × r²) automatically.

Why square yards and acres too?

Flooring and carpet are usually priced per square yard, and land is measured in acres — showing all three saves you from converting by hand.

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unit-convert

Calculating the square footage of a circular room isn't the same formula as a rectangle

Length times width only works for rectangles. Round rooms, triangular sections, and odd angles all need their own formula — and this tool does all three plus the cost math.

2026-09-01

Update history

2026-09-01 Launched: square footage calculator for rectangles, circles, and triangles, with square yard/acre conversion and an optional cost estimate. Entirely client-side.