Area of a Rectangle Calculator
Calculates the area of a rectangle from the measurements you enter. Use any unit, as long as all inputs use the same one.
Result
- Area
- 40
How to use the area of a rectangle calculator
- Enter the length.
- Enter the width.
- The results update as you type, or press Calculate.
- Read the area first, then the supporting figures below it.
Formula
length × width
Worked example
For example, with these inputs:
- Length: 8
- Width: 5
the calculator returns:
- Area: 40
Background
A quick mental estimate before calculating is a powerful check. If a room's floor area comes out at 4,000 square metres or a percentage comes out above 100% when it should not, you know to look again.
Rounding is a common source of small errors. Keep full precision during intermediate steps and round only the final answer to the number of decimal places or significant figures the question asks for.
Frequently asked questions
How does the area of a rectangle calculator work?
It applies this formula: length × width
Can I use any units?
Yes, as long as every input uses the same unit. The answer will be in that unit (squared for areas, cubed for volumes).