Nine shapes, each with its own diagram
Pick a shape — rectangle, square, parallelogram, triangle (two ways), trapezoid, circle, sector or ellipse — and enter its dimensions in whatever units you have; mixed units in the same shape are converted automatically before the area is worked out.
How to use
- Select the shape from the dropdown
- Enter its dimensions, choosing a unit for each if needed
- Press Calculate for the area, with the formula and any unit conversions shown
Common questions
Can I mix units, like giving the length in feet and the width in metres?
Yes — every length field has its own unit dropdown, and the tool converts everything to a common unit before multiplying. The working panel shows exactly which fields needed converting and what they became.
Why did it reject my three-sided triangle?
It checks the triangle inequality (the two shorter sides must add up to more than the longest one) after converting all three sides to the same unit — three numbers that look valid on their own can still fail once mixed units are reconciled, so the check happens after conversion, not before.
Is there a limit on the numbers I can type in?
Each field's whole-number part is capped at six digits as you type, which keeps this tool focused on everyday shapes rather than engineering-scale figures.