Square footage calculator
Rooms in feet and inches or meters. Rectangles, L-shapes, circles and triangles. Add rooms, take away an island, and see what flooring to buy.
Area = length × width. A room 15 ft by 12 ft is 180 sq ft.
A worked example: three rooms, one island
A bedroom, an L-shaped living room and a kitchen island that the new floor goes around. These are the numbers the calculator above gives for the same sizes.
| Room | Sizes | Working | Area |
|---|---|---|---|
| Bedroom | 14′ 6″ × 12′ | 14.5 × 12 | 174.00 sq ft |
| Living room, part A | 18′ × 12′ | 18 × 12 | 216.00 sq ft |
| Living room, part B | 9′ 6″ × 8′ | 9.5 × 8 | 76.00 sq ft |
| Kitchen island (taken away) | 6′ × 3′ | 6 × 3 | −18.00 sq ft |
| Floor to cover | 448.00 sq ft | ||
That is 41.62 m² or 49.78 sq yd. With 10% extra for cutting you buy 492.80 sq ft; at $3.50 per sq ft the flooring costs $1,724.80.
How to calculate square footage
- Measure each wall at floor level, wall face to wall face, in feet and inches. Our guide on how to measure a room covers the order and the usual mistakes.
- Turn inches into feet. Divide the inches by 12: 12′ 6″ is 12.5 ft, not 12.6 ft. This is the most common slip.
- Multiply length by width. 14.5 × 12 = 174 sq ft.
- Split odd shapes into rectangles that do not overlap, work out each one and add them. For a round room use the circle; for an angled corner use the triangle.
- Add every room and take away anything you will not cover: a kitchen island, a fireplace hearth, a stair opening.
- Add extra for flooring: 5 to 10% for a straight lay, 15% or more for diagonal or patterned floors.
Area formulas by shape
length × width15 ft × 12 ft = 180 sq ftrectangle A + rectangle B18 × 12 + 9.5 × 8 = 292 sq ftπ × radius²10 ft across: 3.1416 × 5² = 78.54 sq ft½ × base × height12 ft base, 8 ft high: 48 sq ftInches to decimal feet
Use this when you multiply by hand. The calculator does it for you, so you can type feet and inches as you measured them.
- 1″0.083 ft
- 2″0.167 ft
- 3″0.250 ft
- 4″0.333 ft
- 5″0.417 ft
- 6″0.500 ft
- 7″0.583 ft
- 8″0.667 ft
- 9″0.750 ft
- 10″0.833 ft
- 11″0.917 ft
In meters
The same rule works in meters: 4.2 m × 3.6 m = 15.12 m², which is 162.75 sq ft. Switch the calculator to Meters and it shows square meters first, with square feet beside them. Switching keeps what you typed and converts it.
Square footage of a whole house
For flooring, paint and furniture you need the inside floor area of each room, which is what this calculator gives. A listed house size is measured differently: in the US, the ANSI Z765 standard counts finished living space above ground and measures a detached house from its outside walls, so it comes out larger than the sum of the rooms.
See it on a floor plan
Once the numbers are in, Draw these rooms on a floor plan opens your rectangles and L-shapes in the floor plan maker, side by side, each with its area. There you can move them into place, add doors, windows and furniture at real sizes, and download a PDF to scale.
Questions
How do you calculate square footage?
Multiply the length by the width, both in feet. A room 15 ft long and 12 ft wide is 15 × 12 = 180 sq ft. Turn inches into feet first (divide by 12), split odd shapes into rectangles, and add the parts.
How many square feet is a 12×12 room?
144 sq ft (12 × 12). A 10×12 room is 120 sq ft, 12×14 is 168 sq ft and 20×20 is 400 sq ft.
How do I convert square meters to square feet?
Multiply by 10.764 (exactly 1 ÷ 0.3048²). So 15.12 m² is 162.75 sq ft. To go back, divide square feet by 10.764. One square yard is 9 sq ft.
What if I leave the inches empty?
An empty inches box counts as 0 inches, so 15 ft and 12 ft give 180 sq ft. Some calculators show 0 until every box is filled; this one does not.
How much extra flooring should I buy?
A common rule is 5 to 10% extra for a straight lay in a simple room, and 15% or more for diagonal or herringbone patterns and rooms with many corners. Check the box size and the maker's advice for your product.
Are my rooms saved or sent anywhere?
They are saved in this browser on this device so they are still there when you come back. Nothing you type is sent to us.