Area Calculator
Calculate area for rectangles, circles, triangles, trapezoids, parallelograms, and ellipses in sq ft, sq m, or sq in.
Returns area, perimeter, diagonal.
This calculator finds the area of four common shapes, with full support for both metric and imperial units.
Rectangle: Area = Length × Width
Multiply the two side lengths together. A 10 ft × 8 ft room has an area of 80 ft2. In metric, a 3 m × 2.5 m room has an area of 7.5 m2. The calculator also shows the perimeter (total distance around the shape).
Circle: Area = π × Radius²
Square the radius and multiply by pi (3.14159). A circle with a 5 ft radius has an area of about 78.5 ft2. A circle with a 2 m radius has an area of about 12.6 m2. The result includes the circumference.
Triangle: Area = (Base × Height) / 2
Multiply the base by the height and divide by two. The height must be measured perpendicular to the base, not along the slanted side. A triangle with a 12 ft base and 6 ft height has an area of 36 ft2.
Trapezoid: Area = ((Base1 + Base2) / 2) × Height
Add the two parallel sides, divide by two, then multiply by the height. This is useful for irregularly shaped lots, garden beds, and architectural features.
When to use this calculator:
- Estimating flooring, carpet, or tile for a room
- Calculating material for a garden bed or patio
- Determining paint coverage for a surface
- Solving geometry homework or construction planning
Tips:
- Always use the same unit for all measurements. Do not mix feet and inches or meters and centimeters.
- Use the unit dropdown to switch between meters, feet, inches, yards, centimeters, kilometers, and miles.
- For irregular shapes, break them into rectangles and triangles, calculate each separately, then add them together.