Square Footage Calculator
Measure a room, a floor or a yard and get the area in square feet, square yards and square meters — plus the cost of materials.
How to calculate square footage
Measure in feet and use the formula for the shape:
- Rectangle or square: length × width. A 14 ft × 12 ft room is 168 sq ft.
- Circle: π × radius², or π × diameter² ÷ 4. A 10 ft circle is about 78.5 sq ft.
- Triangle: base × height ÷ 2. A triangle 10 ft wide and 8 ft tall is 40 sq ft.
If a measurement is in inches, divide it by 12 to get feet. For example, 10 ft 6 in is 10.5 ft.
Measuring L-shaped and irregular rooms
Split the space into simple shapes, calculate each one, then add them together. An L-shaped living room might be a 15 × 12 rectangle plus an 8 × 6 rectangle: 180 + 48 = 228 sq ft. For a closet or a bay window, measure it as its own small rectangle and add it in.
Why add extra for waste?
Materials get cut to fit edges, corners and doorways, and some pieces break. Common allowances are:
- Laminate, vinyl plank and carpet: 5% – 10%
- Tile: 10% – 15%, more for diagonal patterns
- Hardwood: 7% – 10%
- Sod: about 5%
Useful conversions
1 sq yd = 9 sq ft · 1 sq m = 10.764 sq ft · 1 acre = 43,560 sq ft
Frequently asked questions
How do I find the square footage of a house?
Measure each room and hallway, calculate their areas and add them up. Official listings usually count finished, heated living space and leave out garages and unfinished basements.
How many boxes of flooring do I need?
Take the total with waste and divide by the square feet per box printed on the package, then round up. If a box covers 20 sq ft and you need 185 sq ft, buy 10 boxes.
How much paint do I need for a room?
For walls, multiply the perimeter of the room by the wall height, subtract doors and windows, and divide by the coverage on the can (often about 350 – 400 sq ft per gallon per coat).
Last reviewed November 14, 2026.
