How to use this calculator
Choose a shape, enter its dimensions in feet, and the area appears instantly. Add more areas for other rooms or oddly shaped spaces; the total and the metric and yard conversions update automatically. Enter a price per square foot to estimate the cost of flooring, tile, carpet, decking or any material sold by area.
Formulas
| Shape | Area |
|---|---|
| Rectangle / square | length × width |
| Circle | π × radius² |
| Triangle | ½ × base × height |
| L-shape | rectangle 1 + rectangle 2 |
| Trapezoid | ½ × (side A + side B) × height |
Measure in feet with decimals (10 ft 6 in = 10.5 ft). If you measured in inches, divide by 12 first; if you measured in metres, multiply the final square-metre figure by 10.764.
Measuring tips
- Measure at floor level along the longest walls, corner to corner, and round to the nearest inch.
- Ignore small alcoves when you’re buying materials with a waste allowance — the allowance covers them. Include them when the exact figure matters (real estate, rent per sq ft).
- For walls, use wall length × height and subtract openings — or use the paint calculator, which handles that.
- For land, 43,560 sq ft = 1 acre; a quarter-acre lot is about 10,890 sq ft.
Common sizes for reference
| Space | Typical area |
|---|---|
| Parking space | 160–180 sq ft |
| Small bedroom | 100–120 sq ft |
| Master bedroom | 200–300 sq ft |
| Two-car garage | 400–600 sq ft |
| Studio apartment | 350–600 sq ft |
| Average new US house | ~2,300 sq ft |
| Tennis court | 2,808 sq ft |
What to do with the number
- Flooring, tile, carpet: add 10% for cuts and waste, or use the tile calculator for exact tile counts.
- Paint: the paint calculator converts wall area to gallons.
- Mulch, gravel, soil: the mulch and gravel calculator turns area × depth into cubic yards and bags.
- Concrete: the concrete calculator for slabs and footings.
- Rent or price comparisons: divide the monthly rent or sale price by square footage to compare properties fairly.
Frequently asked questions
How do I calculate square footage?
Multiply length by width, both in feet. A 12 ft × 10 ft room is 120 square feet. For a room measured in feet and inches, convert inches to a decimal first (6 inches = 0.5 ft), or add a second area for the odd bit.
How do I measure an irregular room?
Break it into rectangles, measure each, and add them up. Pick "L-shape" for two rectangles in one entry, or add as many areas as you need — the total updates as you go.
Does square footage include closets and hallways?
For flooring and paint, yes — measure everything that gets covered. For real-estate "living area", rules vary; most exclude garages, unfinished basements and spaces under 5 ft of headroom.
How many square feet in a square metre?
10.764. The calculator shows the metric equivalent alongside square yards and acres.
Last updated August 27, 2026.