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:
How the Geometry Calculator works
- Identify the shape and which measurements you have.
- Choose the formula (e.g. A = ½bh, A = πr², or Heron’s √(s(s − a)(s − b)(s − c))).
- 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).
More Geometry & Trigonometry calculators
Volume & Surface AreaCubes, cylinders, cones, spheres and prisms.
Pythagorean TheoremFind a missing side of a right triangle.
Triangle SolverLaw of sines, law of cosines, angles and sides.
Circle CalculatorCircumference, arc, sector, chord and tangent problems.
Angles & Parallel LinesAngle sums, polygons, parallel-line and triangle angle rules.
Coordinate GeometryDistance, midpoint, slope and equation of a line.
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