How to use the rectangle area calculator
- Length (m): Length of the rectangle in meters.
- Width (m): Width of the rectangle in meters.
- Select Calculate to see the result. Change any input and calculate again to compare.
Worked example
A 5 m by 4 m rectangle covers 20 m² with an 18 m perimeter.
Formula and assumptions
Length × width = area.
Use consistent units. Irregular shapes must be split into simpler pieces.
Common questions
Why might my result differ from another estimate?
Use consistent units. Irregular shapes must be split into simpler pieces. Keep the same inputs and rounding when comparing tools.
Are my entries saved?
No. Calculations run on your device. Reloading or closing this page may clear your entries.