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Area Calculator

Find the area of common 2D shapes: pick a shape, enter its measurements and get the area in square units, with the formula worked out and conversions to other units.

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Calculator

Square area

25 cm²

A = side²

In mm²
2,500 mm²
In m²
0.0025 m²
In in²
3.875 in²
In ft²
0.02690978 ft²
In hectares
0.00000025 ha

Formula with your numbers

A = side²

A = 5²

A = 25 cm²

Keep analyzing

For estimates only. Double-check the numbers before making important decisions.

Area formulas

ShapeFormula
Squareside²
Rectangle and parallelogrambase × height
Trianglebase × height ÷ 2
Circleπ × radius²
Trapezoid(long base + short base) × height ÷ 2
Rhombuslong diagonal × short diagonal ÷ 2
Ellipseπ × semi-major axis × semi-minor axis

Which measurement to use

  • Height: always measured at a right angle to the base, not along a slanted side.
  • Radius: half the diameter. A circle 10 ft across has a 5 ft radius.
  • Trapezoid bases: the two parallel sides.
  • Ellipse axes: the semi-major and semi-minor axes are half the full length and half the full width.
  • Units: enter every measurement in the same unit (inches, feet, yards, meters and so on).

Square units and conversions

If you measure in feet, the area is in square feet (ft² or sq ft). When you convert area, the length factor gets squared: 1 ft = 12 in, but 1 ft² = 144 in².

UnitEquals
1 ft²144 in²
1 yd²9 ft²
1 m²about 10.7639 ft²
1 m²10,000 cm²
1 hectare10,000 m² (about 2.471 acres)

Common uses

  • Finding the square footage of a room, yard or wall.
  • Estimating flooring, tile, sod or paint sold by the square foot.
  • Checking geometry homework.

Example

A room that measures 12 ft by 15 ft has an area of 180 sq ft (about 16.72 m²). If you add 10% extra flooring for cuts and waste, buy 198 sq ft. A round patio with a 6 ft radius covers about 113.1 sq ft.

  1. Rectangle: 12 × 15 = 180 ft²
  2. With 10% waste: 180 × 1.1 = 198 ft²
  3. Circle: π × 6² = π × 36 = 113.0973 ft²

Common mistakes

  • Using the slanted side of a triangle or parallelogram as the height.
  • Plugging the diameter into the circle formula instead of the radius.
  • Converting area with the length factor: square feet to square inches is × 144, not × 12.

Frequently asked questions

How do I calculate the square footage of a room?

Multiply the length by the width, both in feet. For an L-shaped room, split it into rectangles, find each area and add them: 12 × 10 + 6 × 8 = 168 sq ft.

How do I convert square feet to square yards?

Divide by 9, because a square yard is 3 ft × 3 ft. For example, 180 sq ft is 20 sq yd.

How do you find the area of a triangle?

Multiply the base by the height and divide by 2. A triangle with a 6 in base and a 4 in height has an area of 12 in².

Why does the area of a circle have so many decimals?

Because it uses π, which never ends. The calculator uses full precision for π (3.14159265…), so its answer can differ slightly from one that uses 3.14. Round to whatever you need.

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