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Square Footage Calculator
Find the square footage of a room, wall, yard or lot. Choose a rectangle, circle, triangle or trapezoid, enter the measurements in feet, inches or metric, and get the area in square feet, square yards and acres with an optional cost.
- Square yards
- 20 sq yd
- Acres
- 0.0041 ac
- Cost
- $0.00
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Pick the shape that matches the space.
- Enter the measurements, choosing the unit beside each one.
- Set the quantity if you have several identical areas.
- Add a price per square foot to estimate a cost.
Worked examples
A 15 × 12 ft room
- Area
- 180 ft²
- Square yards
- 20 sq yd
- Acres
- 0.0041 ac
A round patio 10 ft across at $12 a square foot
- Area
- 78.54 ft²
- Square yards
- 8.73 sq yd
- Cost
- $942.48
A trapezoid lot with parallel sides of 60 ft and 40 ft, 30 ft apart
- Area
- 1,500 ft²
- Square yards
- 166.67 sq yd
- Acres
- 0.0344 ac
Measuring an irregular room
Break the space into simple shapes — usually rectangles, sometimes a triangle for an angled corner — work out each one and add them. For an L-shaped room, two rectangles do it.
If you measured in feet and inches, convert the inches to a decimal by dividing by 12: 10 ft 6 in is 10.5 ft. You can also type a fraction such as 10 1/2.
Handy conversions
1 square yard = 9 sq ft. 1 square meter = 10.764 sq ft. 1 acre = 43,560 sq ft. A roofing “square” is 100 sq ft.
Questions people ask
How do I calculate square feet?
Multiply the length by the width, both in feet. A room 12 ft by 15 ft is 180 square feet.
How many square feet is a 10×10 room?
100 square feet, which is about 11.1 square yards or 9.29 square meters.
How do I convert square meters to square feet?
Multiply by 10.764. A 20 m² room is about 215 sq ft.