Shape Area Calculator
Calculate the area of a rectangle, triangle, circle, trapezoid and parallelogram.
Tip: Use the same unit for all dimensions; the result comes out in square units.
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About this digital tool
The area calculator finds the surface of five common plane shapes: rectangle, triangle, circle, trapezoid and parallelogram. Choose the shape, enter the required dimensions (length, width, base, height or radius) and get the area instantly.
The formulas are: rectangle length × width, triangle base × height ÷ 2, circle π × r², trapezoid (base 1 + base 2) ÷ 2 × height and parallelogram base × height. For example, a 5 m × 3 m room has an area of 15 m², a circle with radius 2 has π × 4 ≈ 12.57, while a trapezoid with bases 3 and 7 and height 4 has 20. It is used for calculating construction materials, for land and for geometry homework.
How to use
- Choose the geometric shape.
- Enter the required dimensions.
- See the area in square units.
Frequently asked questions
How is the area of a circle calculated?
Area = π × r², where r is the radius. E.g. for r = 5: 3.1416 × 25 ≈ 78.54 square units.
How is the area of a triangle calculated?
The area is the base multiplied by the height and divided by 2. E.g. base 6 and height 4 give 6 × 4 ÷ 2 = 12.
How is the area of a trapezoid calculated?
Add the two bases, divide by 2 and multiply by the height. E.g. bases 3 and 7, height 4: (3 + 7) ÷ 2 × 4 = 20.
What is the difference between area and perimeter?
Area measures the surface inside the shape (in square units, e.g. m²), while perimeter measures the length of the outline (in linear units, e.g. m). A 5 × 3 rectangle has an area of 15 and a perimeter of 16.