Unit handling
If length and width use the same unit, the result is in square units. For example, meters produce square meters.
Example
A rectangle that is 12 units long and 8 units wide has an area of 12 x 8 = 96 square units. The diagonal is about 14.42 units.
When rectangle area helps
Use area for floors, walls, tables, screens, gardens and other flat rectangular surfaces. Use perimeter when you need the distance around the outside edge.
Common mistakes
Convert units before multiplying. A length in feet and a width in inches will produce a misleading result unless one measurement is converted first.
Last reviewed: 2026-05-17