H1_Geometry Calculator - Area & Perimeter | MultiTool

How it works

Pick a shape (square, rectangle, triangle, circle or trapezoid), enter its dimensions and get the area and perimeter instantly with correct units.

Formulas you will actually use

Geometry questions in real life are usually one of three: how much surface (area — paint, flooring, grass), how much border (perimeter — fences, trim, baseboards) or how much volume (boxes, tanks, concrete).

• The classic trap — radius vs diameter: half of all geometry errors are using the diameter where the radius belongs. Double-check which one your tape measure gave you before trusting any circle formula.
• Paint math: wall area minus doors/windows, divided by the coverage printed on the can (typically ~10 m² or ~350 ft² per liter/gallon per coat) — always budget two coats.
• π is not 3.14 by accident: the calculator uses full floating-point precision; the rounding to 3.14 is only for humans.
• Composite shapes: an L-shaped room is two rectangles; a round table with a rectangular leaf is a circle plus a rectangle. Split, compute, add — that is 90% of practical geometry.

The tool covers the essentials — rectangles, circles, triangles and friends — with the formulas shown beside the results, so the calculator doubles as a reference.

Your privacy

Everything runs entirely in your browser. Nothing you type is ever sent to any server or stored.