Floor Area Calculator
Get the floor area, perimeter and waste-adjusted area for a room. These three numbers feed almost every other flooring and renovation calculator.
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Formula and method
Area is length multiplied by width. Perimeter is twice the sum of length and width. The waste-adjusted area adds the waste percentage to the raw area.
How to measure the inputs
- Run the tape along the floor from wall to wall, not along the skirting.
- Measure both ends of the wall and use the larger value.
- Check ceiling height separately if you also need wall or volume figures.
Worked example
Room length 13.12 ft; Room width 16.4 ft; Waste 10 % → Floor area with waste: 236.81 ft²
Practical tips
- Measure at the widest point of each wall: rooms are rarely perfectly rectangular.
- Note measurements on a sketch so you can reuse them in the other calculators.
- For open-plan spaces, treat each functional zone as its own rectangle.