Geometry Calculators

About these calculators

Geometry has three calculators with the formulas shown beside each result. Area & Perimeter Calculator handles four flat shapes. It takes length and width for a rectangle, a side for a square, the radius for a circle, and the base, height and two other sides for a triangle, and it checks that the three sides could really form a triangle. Pythagorean Theorem Calculator finds the hypotenuse of a right triangle from its two legs, or a missing leg from the hypotenuse and the other leg. Volume Calculator covers five solids: a cube, a rectangular box, a cylinder, a sphere and a cone.

Results come out in whatever unit you used for the inputs, squared for area and cubed for volume, because the tools do not convert units. A circle or sphere needs the radius, so halve a diameter first. The area and volume figures are rounded to two decimals and the Pythagorean result to four, so small shapes can lose detail on screen. The calculators do not handle polygons beyond these four shapes, hollow or partial solids such as pyramids and frustums, or triangles solved from angles. Every calculation happens in your browser, and each page gives a worked example you can compare with your own numbers.

Some numbers to check against. A circle with a radius of 5 has an area of 78.54 and a circumference of 31.42, and a 10-unit diameter means entering 5. A triangle with a base of 6, a height of 4 and two other sides of 5 and 5 has an area of 12.00 and a perimeter of 16.00. In the Pythagorean calculator, legs of 3 and 4 give a hypotenuse of 5.0000, and a hypotenuse of 13 with a known leg of 12 gives the other leg as 5.0000; entering a hypotenuse of 10 with a known leg of 12 returns a message that the hypotenuse must be longer than the known leg. A cylinder with a radius of 3 and a height of 10 has a volume of 282.74, and a sphere with a radius of 6 has a volume of 904.78, both in cubic units of whatever unit you entered.