Rectangle Area Calculator
Compute the area of a rectangle from length and width: A = l × w.
Calculator
Use the Rectangle Area Calculator
Result
—
Formula
A = length × width
Step-by-step
- 1
Enter length and width
Both must be positive.
- 2
Read the area
Area in square units.
Worked example
Example input: a: 8, b: 3
Result: 24
Related tools
- Rectangle Perimeter
2 × (l + w).
Frequently asked questions
What is the formula for the area of a rectangle?
A = length x width — multiply the two perpendicular sides. A rectangle measuring 6 by 4 encloses 24 square units. Enter both sides above and the multiplication happens for you, decimals included.
How do I find one side if I know the area?
Divide: width = area divided by length. A rectangle with area 48 and a length of 8 must be 6 wide. The division is just the area formula rearranged, so it always closes back to the original two numbers.
Does it matter which side I call length?
Not at all — multiplication is commutative, so 6 x 4 and 4 x 6 both give 24. The label only matters for orientation on a sketch, never for the number that comes out.