Room Area Calculator
Find the floor area and perimeter of a rectangular room. Use the measurements as a starting point for flooring, tile or paint estimates.
Your result
- Floor area
- 20 m²
- Perimeter
- 18 m
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Formula
Area = length × width; perimeter = 2 × (length + width).
Worked example
The initial example uses the following assumptions. Its result is computed by the same engine as the calculator. Measurements are metric and money amounts use USD; these are illustrative inputs, not market prices.
- Room length
- 5 m
- Room width
- 4 m
- Floor area: 20 m²
- Perimeter: 18 m
Assumptions and limitations
Measure internal dimensions consistently. Split an L-shaped floor into non-overlapping rectangles and add their areas. Do not add those rectangles' perimeters: shared edges are internal.
Questions about this calculation
How should I handle an irregular room?
Split it into simple shapes and add their non-overlapping areas. This tool handles one rectangle at a time.
Is floor area the same as wall area?
No. Wall area requires perimeter and height, with doors and windows considered separately.
Useful next steps
- Flooring Cost Calculator
Estimate flooring materials and installation for a rectangular room. Keep the material area you buy separate from the floor area being installed.
- Paint Calculator
Estimate paint for four walls, allowing for openings, coats and waste. Enter the coverage specified for your chosen product.
- Tile Calculator
Estimate the number and cost of tiles for a rectangular floor. Add a cutting allowance, then round up to individual whole tiles.