Home & Construction
Area Calculator
Updated Aug 20, 2026 Reviewed Aug 20, 2026
Calculate the area of a rectangle from its length and width, then convert the result between metric and imperial area units.
Rectangle dimensions
Enter length and width
Result
Calculation summary
Enter values to see the result
Your result, breakdown, assumptions, and warnings will appear here.
Visual guide
Rectangle dimensions
How to use this calculator
- 1Enter the rectangle length and width using positive numbers.
- 2Choose the unit shared by both measurements.
- 3Choose the area unit you want for the main result, then select Calculate area.
Formula
Area = length × width
The calculator converts both dimensions to meters, multiplies them, and then converts the square-meter result into the selected area unit.
Calculation steps
- Validate that length and width are finite positive numbers.
- Convert each dimension into meters using the selected length unit.
- Multiply the normalized length by the normalized width to obtain square meters.
- Divide by the selected area unit factor and display the converted result.
Worked example
A room measuring 12 ft by 10 ft covers 120 ft², which is approximately 11.1484 m².
Assumptions
- The measured shape is a rectangle with four right angles.
- Length and width use the same selected input unit.
- Conversions use the international foot, where 1 ft equals exactly 0.3048 m.
- Displayed values are rounded, while calculations keep full floating-point precision.
Sources
Frequently asked questions
How do I calculate the area of a rectangle?
Multiply the rectangle length by its width. Both measurements must use the same length unit before multiplication.
Why are length units squared in an area result?
Area measures a two-dimensional surface. Multiplying one length by another produces a squared unit such as m² or ft².
Can I convert square feet to square meters?
Yes. Enter the dimensions in feet and choose square meters as the result unit, or choose square feet to keep the original unit.
Does this calculator work for circles or triangles?
No. This version calculates rectangles only. Circles and triangles use different formulas.
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