Area Calculator

Area Calculator works out the area of the shapes that actually come up: rectangle, square, circle, triangle, trapezium, parallelogram, ellipse, sector, ring and regular polygon.

Each shape shows its formula with your numbers substituted in, not just the result. For a triangle given three sides it uses Heron's formula and shows the semi-perimeter step; for a sector it shows the fraction of the full circle you asked for. This matters for coursework, and it matters just as much when a result looks wrong and you need to see where it came from.

Perimeter, or circumference, is given alongside the area, because the two are almost always needed together. Working out flooring needs the area; working out skirting board or fencing needs the perimeter, and having to open a second tool for the second half of the same job is a nuisance.

Units are handled properly. Enter measurements in metres, centimetres, feet or inches, and the result is given in the matching square unit along with conversions, so square feet to square metres does not need a separate calculation. Mixed units in one shape are converted before the area is worked out rather than after.

Everything is worked out inside your browser. Nothing you enter is uploaded, logged or stored, which matters for the financial calculators in particular: the figures you put into them are nobody else's business.

• Ten shapes, each with its own formula
• Perimeter or circumference given with the area
• Heron's formula for a triangle from three sides
• Metric and imperial input, with the result converted both ways
• Working shown, not just the answer
• Larger units such as acres and hectares where they are useful
• Runs in your browser

The area calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Working out flooring, paint or turf for a room or garden
• Calculating land area for a listing or a sale
• Geometry homework where the formula must be shown
• Sizing a tarpaulin, a cover or a sheet of material
• Checking a quote that was priced by the square metre