Can I use this for an irregular room shape?

Split the irregular shape into rectangles/triangles/etc., compute each separately, and add them.

Does it matter what unit I enter?

No — the calculator is unit-agnostic; the output unit is simply the square of whatever unit you entered.

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Math & Everyday

Area Calculator

Area of a square, rectangle, triangle, circle, or trapezoid from its dimensions.

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About the Area Calculator

Computes the area of five common shapes — square, rectangle, triangle, circle, and trapezoid — from their dimensions, using the standard geometry formula for each.

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How to use it

Pick a shape.
Enter its dimensions.
Read the computed area.

Formula

Square: side². Rectangle: length × width. Triangle: ½ × base × height. Circle: π × radius². Trapezoid: ½ × (side a + side b) × height.

Worked example

A circle with radius 5: π × 5² = 78.54. A rectangle 6 long × 4 wide: 6 × 4 = 24.

Area formulas by shape

Area formulas by shape
Shape	Formula
Square	side²
Rectangle	length × width
Triangle	½ × base × height
Circle	π × radius²
Trapezoid	½ × (a + b) × height

Interpreting your result

Unit-agnostic — enter whatever unit you want the area expressed in. Distinct from this site's Square Footage Calculator, which is built for summing multiple real rooms with a metric/imperial toggle rather than single-shape geometry reference.

Recommendations

• For an irregular shape, split it into these 5 basic shapes and add the areas together.
• Triangle height must be measured perpendicular to the chosen base, not along a slanted side.
• Trapezoid's two 'a'/'b' sides must be the parallel pair.

Frequently asked questions

This is a general single-shape geometry reference tool; Square Footage Calculator is built for summing multiple real rooms and has a metric/imperial toggle.