Square footage calculator
Floor area of one or more rooms, with waste and cost per square foot.
About this calculator
This square footage calculator adds up the floor area of one or more rooms in square feet or square metres. Enter each room's length and width on its own line.
Add a waste allowance and a price per square foot to estimate how much flooring, carpet or tile to buy and what it will cost.
How it works
Each room is length × width. The rooms are added together, then the waste allowance is added on top, since flooring needs extra for cuts and mistakes.
Last reviewed:
Worked example
- Measure in: Feet
- One room per line: length, then width: 12 14; 10 11.5; 8 6
- Extra for waste and cuts: 10%
Total floor area: 331 ft² (30.75 m²)
Common questions
How do I calculate square footage?
Measure the length and width in feet and multiply them. A room 12 ft by 14 ft is 168 square feet. For an L-shaped room, split it into two rectangles and add them.
How much extra flooring should I buy?
About 5% to 10% for simple rooms, and 15% or more for diagonal layouts, patterned tiles or rooms with many corners.
How many square feet are in a square metre?
About 10.76. One square foot is 0.0929 square metres.
The story behind it
Where the idea came from: Builders and appraisers measure floor area to agreed standards, such as ANSI Z765 for homes in the US.
Floor area sets the price of homes, rents and building materials, so how it's measured matters. Standards spell out what to include, such as which walls to measure from and how to count stairs. For a flooring job, the simple sum of each room's length times width is what you need, plus a little extra.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, so please double-check anything important.
- Spotted a mistake? Tell us and we'll look into it.
After 15 years as a mathematics educator, I built CalculStore to give students, teachers, professionals and anyone working with numbers simple, reliable tools.
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