Square Footage Calculator
Square feet for a room or a whole floor, typed in feet and inches, with odd shapes and cut-outs.
Works in your browser. Nothing you type is sent to us.
What you are measuring
Type 12' 6" or 12.5 for twelve and a half feet; 6 1/2" works too. For an L-shaped room, add it as two rectangles. Tick Take away for an island, a fireplace or a stairwell.
Material, optional
Flooring: add 5–10% for cuts, 15% or more for a diagonal or herringbone layout.
Each area
| Area | Working | sq ft |
|---|
Worked out in your browser as you type. Nothing you type is sent to us.
Square Footage Calculator at a glance
- Price
- Free
- Data sent to us
- None, it runs in your browser
- Sign-up
- Not needed
- Shapes
- Rectangle, triangle, circle, trapezoid
- Units
- Feet and inches, or metres
- Gives
- Sq ft, sq yd, m², acres, boxes, cost
How to use Square Footage Calculator
- Measure the spaceMeasure the length and width of each part of the room. Split an L-shaped room into two rectangles.
- Type each areaType the measurements as you read them, such as 12' 6". Press Add another area for each extra part, and tick Take away for an island or an opening.
- Read the totalThe total shows in square feet, square yards, square metres and acres. Add a waste allowance, a price or the coverage of one box to see what to buy.
Type each area the way you read it off the tape, 12' 6" or 12.5, choose its shape (rectangle, triangle, circle or trapezoid) and add as many areas as the space needs. Tick Take away for an island, a hearth or a stair opening. The total shows in square feet, square yards, square metres and acres, with the working for every area, and an optional waste allowance, price and box coverage turn it into what to buy and what it costs. Metres and centimetres work too.
How it works
Square Footage Calculator is a web page that does its work on your own device. Everything you type or choose is worked out by your browser and never sent to a server, so nothing is stored and there is nothing to delete. There is no account, no sign-up and no limit on how often you use it.
Straight to one job
Flooring Calculator · Square Meter Calculator
How square footage is worked out
Square footage is length times width, in feet. A room 12 feet by 10 feet 6 inches is 12 × 10.5 = 126 square feet. The inches have to become a fraction of a foot first: 6 inches is half a foot, 3 inches a quarter, 9 inches three quarters. That conversion is where most hand sums go wrong, so this calculator takes the measurement the way it is read off the tape, 10' 6", and does it for you.
Rooms that are not rectangles
Break the space into pieces you can measure. An L-shaped room is two rectangles. A bay window is a trapezoid: the wall side and the window side are the two parallel sides, and the depth is the height. A round patio or a rug is a circle, measured across the middle. A gable wall above the eaves is a triangle. Add every piece as its own area, and tick Take away for anything inside the outline that does not get the material, such as a kitchen island, a fireplace hearth or a stair opening.
| Shape | Formula | Example |
|---|---|---|
| Rectangle | length × width | 12' × 10' 6" = 126 sq ft |
| Triangle | base × height ÷ 2 | 20' × 6' ÷ 2 = 60 sq ft |
| Circle | π × (diameter ÷ 2)² | 10' across = 78.54 sq ft |
| Trapezoid | (top + bottom) ÷ 2 × height | (6' + 10') ÷ 2 × 3' = 24 sq ft |
Square feet, square yards, square metres and acres
There are 9 square feet in a square yard, because a yard is 3 feet and 3 × 3 = 9. Carpet is often priced by the square yard, so divide the square footage by 9 to compare quotes. One square metre is 10.764 square feet, and one acre is 43,560 square feet, about nine tenths of an American football field, not counting the end zones.
Buying flooring, tile and sod
Measured area is what the floor covers; what you buy has to be more, because boards and tiles are cut at walls and doorways and some pieces break. Five to ten percent extra is usual for a straight layout, and fifteen percent or more for a diagonal or herringbone pattern or a room with many corners. Type the coverage printed on one box and the calculator rounds the box count up, since stores sell whole boxes.
What it does
- Feet and inches typed naturally: 12' 6", 12.5, 6 1/2"
- Rectangle, triangle, circle and trapezoid areas, as many as you need
- Take away islands, hearths and openings
- Square feet, square yards, square metres and acres at once
- Waste allowance, boxes to buy and cost
- Metres and centimetres as well as feet
- The working shown for every area
Questions
How do I calculate square footage?
Multiply the length by the width, both in feet. A room 12 feet by 10 feet is 120 square feet. If a measurement has inches, turn them into a fraction of a foot first by dividing by 12: 10 feet 6 inches is 10.5 feet. The calculator does that conversion for you.
How do I measure an L-shaped room?
Split it into two rectangles that do not overlap, measure each one and add the two areas. Press Add another area for the second rectangle.
How many square feet are in a square yard?
Nine, because a yard is 3 feet and 3 × 3 = 9. Divide square feet by 9 to get square yards.
How do I convert square feet to square metres?
Multiply by 0.0929, or divide by 10.764. The calculator shows both at once, and you can switch the units to metres and centimetres.
How many square feet are in an acre?
An acre is 43,560 square feet, or about 4,047 square metres.
How much extra flooring should I buy?
Five to ten percent for a straight layout and fifteen percent or more for diagonal or herringbone patterns. Check the installation guide that comes with the product, which may ask for a specific amount.
Does it work out wall area for paint?
Yes, treat each wall as a rectangle (width × height) and tick Take away for doors and windows. Check the paint can for how many square feet a gallon covers.
Is anything sent anywhere?
No. The sums are done in your browser and nothing is stored.
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