Area Calculator

What It Does

This calculator turns the measurements of a flat shape into its area. Choose a rectangle (or a square), a triangle or a circle, enter the dimensions that shape needs in millimetres, centimetres, metres, inches, feet or yards, and it applies the matching formula: length × width, ½ × base × height, π × r², base × height for a parallelogram, or π × a × b for an ellipse. The result is the area in the unit you measured in, squared, with square metres and square feet beside it; a dimension that is zero, negative or missing is rejected and reported, not guessed.

Real-World Usage

Area answers what a surface covers: flooring and tiles, paint and wallpaper, turf and seed, land and plots, or the cross-section of a pipe. Measure the room in the unit your tape holds — 12 ft × 10 ft = 120 ft², about 11.1 m² — and the two counterparts let you price a material quoted in the other system without converting by hand.

Local Context

Metric readers work in square metres, where a hectare is 10,000 m² and a square kilometre a million; US and UK readers work in square feet (1 ft² = 0.09290304 m²) and square yards (1 yd² = 9 ft²). Because the site serves every country from one page, the calculator reports both systems side by side instead of switching the answer to a local unit, so one figure is never read at the wrong scale.

Which shape do I need — rectangle, triangle or circle?

A rectangle (or a square, which is a rectangle with equal sides) covers floors, walls, plots and any surface with two sides at a right angle. A triangle covers a gable end, a ramp or any three-sided surface, and it is exactly half of the rectangle with the same base and the same height. A circle covers a round table, a round pool or the cross-section of a pipe. Pick the shape whose outline matches the surface and enter only the measurements that shape asks for.

Why is the result in square metres or square feet and not in metres?

Area is a length multiplied by a length, so the unit is multiplied by itself: 5 m × 4 m = 20 m², and the same numbers typed in feet give 20 ft². A single length never adds up into an area — 5 m + 4 m = 9 m is a line, not a surface. The result is shown in the unit you measured in, with square metres and square feet beside it, so either system can be read: 1 ft² = 0.09290304 m² exactly.

Is the triangle's height one of its sides?

Not necessarily. The height is the perpendicular distance from the base to the opposite corner, measured at a right angle to the base, and in an obtuse triangle it falls outside the figure. In a right triangle the two legs are the base and the height. With ½ × base × height, a base of 6 m and a height of 4 m give 12 m².

Why does the calculator refuse a measurement of zero or a negative number?

A side of length zero is not a surface, so the calculator reports no area instead of a misleading 0 m², and a negative length has no geometric meaning at all. The field is refused with an error rather than squared into a positive figure in silence, and every value on the page stays 0 with the unit named — never an empty box, never an infinite figure.