Geometry Calculators

Geometry calculators get used for two very different jobs: schoolwork, where the method matters, and practical measuring, where the answer has to be in units you can buy things in. These pages do both. Each shows the formula with your measurements substituted in, and each converts the result into the other common units, because a floor area in square metres is no use when the tiles are sold by the square foot.

Flat shapes

The area calculator covers eleven shapes in one page and is the place to start. Where a shape needs more than area -- angles, the third side, the inscribed and circumscribed radii -- it has a page of its own: the triangle calculator, right triangle calculator, circle calculator and regular polygon calculator. The perimeter calculator handles the measurement you need when you are buying edging, skirting or fencing rather than covering.

Solids

For volume and surface area there is a general volume calculator and a surface area calculator, plus dedicated pages for the sphere, cylinder and cone. Volume in litres is given alongside cubic metres, which is the conversion people most often need and most often get wrong by a factor of a thousand.

Coordinates and angles

The distance formula, midpoint and slope calculators work on two points and show the substitution, and the trigonometry calculator and degrees to radians converter cover the angle work around them.