Geometry Calculators - Free Online with Formulas

Area Calculator

Find the area of a rectangle, triangle, circle, trapezoid, parallelogram, ellipse, sector or regular polygon — one page for every common shape.

Enter any one of radius, diameter, circumference or area and get the other three, plus the exact value in terms of pi.

Find a cone's volume, slant height, curved surface and total surface area from its radius and height, or from its slant height.

Find a cylinder's volume, surface area and capacity in litres from its radius and height — or work backwards from a required…

Area and volume formulas for every common shape, the unit conversions that trip people up, and a real concrete-slab example worked from…

Find the perimeter of a rectangle, triangle, circle, parallelogram, trapezoid, regular polygon or ellipse — the distance all the way round.

Find the area, perimeter, angles, apothem and radius of a regular polygon from its side length, apothem or circumradius.

Find a missing side of a right triangle, or check whether three lengths form one, with the exact answer and both acute…

Find a rectangle's area, perimeter and diagonal from its sides — or work backwards from the area, perimeter or diagonal to a…

Solve a right triangle from any two of its measurements, including sides, angles, the altitude to the hypotenuse and both circle radii.

Find a sphere's volume, surface area, radius, diameter or circumference from any one of them, with the working shown.

Find the surface area of a box, cube, sphere, cylinder, cone, pyramid, prism or hemisphere, with each face listed separately.

Find the area, perimeter and median of a trapezoid from its two parallel sides and either the height or the two slanted…

Solve any triangle from three sides, two sides and the angle between them, or two angles and a side — with area,…

Find the volume of a box, cube, sphere, cylinder, cone, pyramid, prism or hemisphere — with the answer converted to litres and…