To find square footage, multiply length by width. A 12 × 10 ft room is 120 square feet. Real rooms are rarely perfect rectangles, though, so the calculator below lets you add as many shapes as you need (rectangles, triangles and circles) and adds them up for you. It converts to square yards and square meters, adds a waste allowance for flooring or tile, and estimates the cost if you enter a price per square foot.
Square Footage Calculator
Break an odd-shaped room or yard into simple shapes and add them up. Results update as you type.
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Circle uses the diameter (the full width across). Triangle uses base × height ÷ 2, where height is measured straight out from the base.
How to measure a room in 4 steps
A rough drawing on paper is enough. Mark doors, closets and any jogs in the walls.
Draw lines so every part is a simple shape. An L-shaped room becomes two rectangles.
Measure at floor level and round up to the next inch. Write every number on the sketch.
Enter each shape in the calculator. It totals them and converts the units.
Tip for inches: convert them to decimal feet by dividing by 12. Six inches is 0.5 ft, so 10 ft 6 in becomes 10.5. Or switch the calculator to inches and enter everything in inches.
Odd shapes: split them, then add
Here’s an L-shaped living room broken into two rectangles. The main area is 20 × 12 ft and the nook is 10 × 8 ft:
= 240 sq ft
= 80 sq ft
Total: 240 + 80 = 320 sq ft
The same idea works for a bay window (a rectangle plus a triangle), a round patio (a circle), or a yard with a curved edge (a rectangle plus half a circle: enter the full circle and divide its area by two).
Area formulas at a glance
| Shape | Formula | Example |
|---|---|---|
| Rectangle or square | Length × width | 12 × 10 ft = 120 sq ft |
| Triangle | Base × height ÷ 2 | 8 × 6 ft ÷ 2 = 24 sq ft |
| Circle | 3.1416 × (diameter ÷ 2)² | 10 ft across = 78.5 sq ft |
| Half circle | Circle area ÷ 2 | 10 ft across = 39.3 sq ft |
How much extra to buy (waste factor)
Flooring and tile get cut to fit walls, corners and doorways, and the offcuts are lost. Add the waste percentage in the calculator before you order. These are common rules of thumb; your installer may suggest more for complex rooms.
| Material | Typical extra | Go higher when… |
|---|---|---|
| Laminate or vinyl plank | 5–10% | The room has many corners or closets |
| Hardwood | 7–10% | Boards vary in color and you’ll sort them |
| Tile, straight layout | 10% | Tiles are large or the room is small |
| Tile, diagonal or herringbone | 15–20% | Every edge piece needs an angled cut |
| Carpet | About 10% | The room is wider than one roll and needs seams |
| Sod or pavers | 5–10% | The area has curves |
Unit conversions
| From | To | Do this |
|---|---|---|
| Square feet | Square yards | Divide by 9 |
| Square feet | Square meters | Multiply by 0.0929 |
| Square meters | Square feet | Multiply by 10.764 |
| Square feet | Acres | Divide by 43,560 |
| Square inches | Square feet | Divide by 144 |
What counts toward a home’s square footage?
For a flooring or paint project, you measure exactly the surface you’re covering. A home’s official square footage, the figure on a listing or an appraisal, follows different rules. Many U.S. appraisers use the ANSI Z765 standard, which generally counts finished, heated living space above ground, measured from the outside of the exterior walls. Garages, unfinished basements and open porches are usually listed separately. That’s why your room-by-room total won’t match the number on the listing, and that’s normal.
Related calculators
- Paint calculator: turns a room’s size into gallons of paint.
- Mulch calculator and gravel calculator: take a garden bed or path area and give you cubic yards and bags.
- Concrete calculator: turns the area of a slab plus its thickness into bags or yards.
Frequently asked questions
How many square feet is a 12 × 12 room?
144 square feet, or 16 square yards. If you’re buying flooring, add 5–10% for cuts, so plan on about 152–159 square feet.
How do I calculate square footage with inches?
Either convert the inches to decimal feet (inches ÷ 12) before multiplying, or multiply in inches and divide the result by 144. A 132 × 120 inch room is 15,840 square inches, which is 110 square feet.
Do I include closets when measuring for flooring?
Yes, if the flooring continues into them. Measure each closet as its own small rectangle and add it to the calculator with the “Add another shape” button.
Is square footage the same as square feet?
Yes. “Square footage” is just the total area expressed in square feet. One square foot is a square that measures 1 foot on each side.
