Geometry calculators

Geometry calculators get used for everything from homework checking to room planning to figuring out whether a piece of furniture will actually fit through a doorway. The tools here cover the most-asked geometry questions: triangles (right and oblique), circles, common shape areas, and the distance between two points on a coordinate plane.

The Pythagorean theorem calculator finds any one side of a right triangle given the other two, with the formula shown so you can verify the arithmetic. For non-right triangles, the law of cosines and Heron's formula handle area-from-three- sides and side-from-two-sides-and-an-angle. The circle calculator derives radius, diameter, circumference, and area from any one of those — type the radius, get the rest.

The distance between points tool computes the straight-line distance between two coordinate pairs (the same formula that powers GPS waypoint calculations when you flatten a small region of the Earth). The golden ratio calculator returns the φ-related companion of any number — useful for design proportions, photography, and architecture rules of thumb. Common areas (square, rectangle, triangle, trapezoid, ellipse) round out the set, each with its formula labelled. For graphing or 3D modelling tasks, dedicated tools (Desmos, GeoGebra) are better suited; these calculators are for the numerical case where you know the formula and just need the answer.