Rectangle geometry
Area calculator
Enter the length and width of one rectangular floor, ceiling, wall or measured section to calculate its exact area in metric or U.S. customary units.
Rectangle geometry
Result
How the area calculation works
Use this calculator for one rectangular floor, ceiling, wall or measured section when you know its length and width. The same physical measurement stays exact when you switch unit systems.
How to use it
- Measure the length and width of the same rectangular floor, ceiling, wall or section.
- Choose metric or U.S. customary units and enter both positive measurements.
- Calculate the area, then check the dimensions before using the result for planning.
Formula
Area = length × width. Measurements are converted exactly before multiplication; only the displayed value may be rounded.
Example
For a surface 4.2 m long and 3 m wide: 4.2 × 3 = 12.6 m².
Assumptions
- The surface is rectangular and both measurements describe that same surface.
- The calculator uses only the measurements you enter and adds no allowance or hidden default.
Limitations
- Openings and cut-outs are not subtracted.
- Perimeter, material quantities, packages, waste and prices are not calculated.
- Irregular, curved and combined shapes are outside this calculator.
Area questions
Is area the same as perimeter?
No. Area measures the surface inside a shape in square units; perimeter measures the distance around it in length units.
Can I switch between square metres and square feet?
Yes. Switching the unit system preserves the same physical dimensions and exact canonical result.