Geometry Calculator

Find the area and perimeter of triangles, rectangles, circles, trapezoids and polygons, with the formula and substitution shown. Try “area of a triangle with sides 7, 8, 9” (Heron’s formula).

Try an example:

What you can do with the Geometry Calculator

Area and perimeter of triangles, rectangles, circles and polygons.

Enter your values or describe the problem in the calculator above. Review the result and the explanation before using it in homework, study or practical calculations.

Example input

e.g. area of a triangle with sides 7, 8, 9

How the Geometry Calculator works

  1. Identify the shape and which measurements you have.
  2. Choose the formula (e.g. A = ½bh, A = πr², or Heron’s √(s(s − a)(s − b)(s − c))).
  3. Substitute, calculate and include square units for area.

Frequently asked questions

What is Heron’s formula?

It gives a triangle’s area from its three sides: with s = (a + b + c) ÷ 2, area = √(s(s − a)(s − b)(s − c)).

What is the difference between area and perimeter?

Perimeter is the distance around a shape (length units). Area is the space inside it (square units).

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Math Solver can make mistakes. Please double-check important steps and calculations.