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Simple Calculators

Area Calculator

Calculate the area of any geometric shape with instant unit conversion

Area Calculator

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Quick summary

An area calculator computes the surface area of 2D geometric shapes. Area is measured in square units (e.g., m², ft², cm²). All formulas below are standard Euclidean geometry results.

Reviewed by Simple Calculators TeamLast reviewed

How to use this calculator

  1. Enter the inputs requested by the calculator.
  2. Choose the units or options that match your situation and review the assumptions.
  3. Run or update the calculation to see the result.
  4. Review the result, breakdown, and formulas shown on the page.
  5. Check the inputs, units, dates, and limitations before saving or sharing the result.

Area Formulas

Circle

A=πr2C=2πrA = \pi r^2 \qquad C = 2\pi r
r
Radius of the circle
π
≈ 3.14159265…

Worked example

Circle with radius 5 m

Given
r = 5 m
Calculation
A=π×52=25πA = \pi \times 5^2 = 25\pi
Result
≈ 78.54 m²

Triangle

A=12bhA = \frac{1}{2} b h
b
Base length
h
Perpendicular height

Worked example

Triangle with base 10 m, height 8 m

Given
b = 10 m
h = 8 m
Calculation
A=12×10×8A = \frac{1}{2} \times 10 \times 8
Result
= 40 m²

Trapezoid

A=(b1+b2)2×hA = \frac{(b_1 + b_2)}{2} \times h
b₁, b₂
The two parallel bases
h
Height (perpendicular distance between bases)

Worked example

Trapezoid: bases 6 m and 10 m, height 5 m

Given
b₁ = 6 m
b₂ = 10 m
h = 5 m
Calculation
A=(6+10)2×5A = \frac{(6 + 10)}{2} \times 5
Result
= 40 m²

Frequently asked questions

What is the formula for the area of a circle?

A = π × r², where r is the radius. The circumference is C = 2πr. For example, a circle with radius 5 m has area = π × 25 ≈ 78.54 m².

How do I find the area of an irregular shape?

Decompose the irregular shape into standard geometric shapes (rectangles, triangles, circles), calculate each area separately, and add them. Alternatively, for very irregular shapes, use the Shoelace formula if you know the coordinates of the vertices.

What is the difference between area and perimeter?

Area is the amount of 2D space a shape occupies, measured in square units. Perimeter is the total length of the boundary of a shape, measured in linear units. A 10×5 rectangle has area = 50 m² and perimeter = 30 m.

How do I convert square feet to square meters?

1 square foot = 0.0929 square meters. To convert: multiply square feet by 0.0929. For example, 500 sq ft = 500 × 0.0929 = 46.45 m². The calculator does this automatically in the unit conversion table.

Key terms

Area
The measure of the 2D surface enclosed by a shape, expressed in square units (cm², m², ft²).
Perimeter
The total length of the outer boundary of a 2D shape.
Radius
The distance from the center of a circle to its edge. Diameter = 2 × radius.
Contribution Margin
Not applicable here — in geometry, the "base" and "height" are the two inputs to the triangle area formula: A = ½ × b × h.

Methodology, sources & limitations

This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.

For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.