Start with the right measurement
Accurate area starts with a sketch. Break an L-shaped room, patio, or floor into rectangles that do not overlap, then keep the measured sections visible so another person can check your takeoff.
How to use this calculator
- 01Length and width: Finished dimensions for each rectangular section.
- 02Sections: Add rooms or non-overlapping portions separately.
- 03Waste: A material allowance applied once to the combined area.
The result is the measured area plus an optional planning quantity. Converted units are shown for comparing product packaging, but the original unit remains the source measurement.
Units: Imperial inputs are feet; metric inputs are metres. For odd dimensions, convert inches to decimal feet before multiplying.
How the calculation works
Each area = length × width. Combined area is the sum of every section.A 12 × 10 ft room plus a 6 × 4 ft closet totals 144 ft² before waste.
Worked examples
L-shaped room
- Sketch the shape as a 12 × 10 ft rectangle and a 6 × 4 ft extension.
- Calculate 120 + 24.
- Apply 10% material waste only after adding the two areas.
Result: The measured area is 144 ft²; the planning quantity is 158.4 ft².
Two flooring zones
- Measure a 3.2 m × 4.5 m living area: 14.4 m².
- Measure a 1.8 m × 2.0 m entry: 3.6 m².
- Add the sections without converting one twice.
Result: The total is 18.0 m² before the installation allowance.
How to measure
- 01Measure each rectangle at its longest finished edges.
- 02Divide L-shaped spaces into non-overlapping rectangles.
- 03Check the sketch against doors, cabinets, steps, and fixed obstructions.
Common mistakes to avoid
- Overlapping sections
- Mixing feet and metres
- Applying waste twice
Limits of this estimate
Irregular boundaries, off-square rooms, and installation patterns may require additional allowance or a more detailed takeoff.
Frequently asked questions
Can I add several rooms?
Yes. Add one section for each rectangular room or portion.
Why show both unit systems?
The converted total helps compare products sold in different units.