Rectangle Area Calculator
Calculate the area and perimeter of a rectangle from length and width in any unit, free and instant in your browser.
Enter Values
Shape
How to use this calculator
- Enter the length and width.
- Press Calculate for the area.
How it works
The area of a rectangle is length × width. With both sides in metres, the area is in square metres (m²).
Worked example
4 m × 3 m. Area = 4 × 3 = 12 m².
Common mistakes
- Mixing units — convert both sides to the same unit before multiplying.
- Forgetting a waste allowance when buying flooring or tiles from the area.
Frequently asked questions
Can I mix units, like metres and centimetres?
Convert both sides to the same unit first. Metres × metres gives m²; centimetres × centimetres gives cm².
How do I get area for flooring or tiles?
Use length × width for the floor area, then add ~10% for cuts and waste. The tile calculator does this for you.
Related tools
- Triangle Area Calculator
- Circle Area Calculator
- Tile Calculator
- Cube Volume Calculator
- Cylinder Volume Calculator
- Sphere Volume Calculator
Explore more in Geometry, Shape, Area & Volume.
Cite this tool
Zerdly. (2026). Rectangle Area Calculator. Retrieved from https://www.zerdly.com/tools/rectangle-area-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.