Geometry Calculator
Eleven shapes, every common quantity. Pick a shape, type the dimensions, get areas, perimeters, surface areas, volumes, and diagonals where they apply.
Areas, perimeters, surface areas and volumes for 11 common 2D and 3D shapes.
2D shapes covered
Rectangle, square, triangle (base × height), circle, and trapezoid. For each, the calculator gives area; where it makes sense, also perimeter and key diagonals. Note that for a general triangle without a right angle you should use the trigonometry calculator to find the area via Heron’s formula or 1/2 ab sin(C).
3D shapes covered
Cube, cuboid, sphere, cylinder, cone, and square pyramid. For each, the calculator returns volume, total surface area, and — for the pyramid and cone — the slant height that you actually need to compute the lateral surface.
Why surface area matters
Surface area is the quantity that drives heat loss, paint cost, packaging material, and skin/lung exposure in biology. For two solids of equal volume the one with larger surface area cools faster, costs more to coat, and is easier to react with chemically. Engineers spend a surprising amount of time reasoning about the surface-to-volume ratio of their designs.