A plain rectangle (SF1).
12 ft × 10 ft = 120.00 ft².
Square Footage Calculator
Add up the square footage of one or more rooms, including feet-and-inch measurements and extra for waste.
Results
Enter your numbers to see the results.
| Room | Shape | Area | Square yards |
|---|
- Project subtotal
- Waste
- Total with waste
Square yards: subtotal , waste , total .
This is the floor or surface area, not a materials order by itself. Add waste if you are buying flooring or tile, then use the paint, concrete, paver, deck, or mulch and gravel calculators to turn area into gallons, bags or boards. Measure twice; an inch off on a long wall adds up.
Last reviewed: November 5, 2026
Add one or more rooms and build each one from rectangles, circles and triangles. Every side can be entered in feet, inches or both — 12 ft 6 in by 10 ft 3 in is fine, and so is 0 ft 18 in. An L-shaped room is two rectangles. A waste percent (up to 50%) adds extra square footage for cuts and mistakes when you order material. The page stops at area plus waste; it does not price the job.
How to use it
- Start with one room. Add more rooms if you are totaling a whole floor or several spaces.
- Pick a shape: rectangle (length and width), circle (diameter) or triangle (base and height). A room can hold more than one shape.
- Enter each dimension in feet, inches or both. Inches-only works: 0 ft 18 in is 1.5 ft. Inches are not rolled back into feet before dividing by 12, so 18 in is always 18 ÷ 12.
- For an L-shape, add two rectangles rather than guessing one size.
- Optional: enter a waste percent if you are ordering flooring, tile or a similar material. The default is 0%.
- Read each shape’s area, each room’s total, the project subtotal, the waste amount and the total with waste. An optional square-yard view divides those areas by 9.
How it works
Length in feet = feet + (inches ÷ 12).
- Rectangle = length × width.
- Circle = π × (diameter ÷ 2)², with π = 3.1415926535897932384626433832795.
- Triangle = (base × height) ÷ 2.
- Each displayed area line is the exact area rounded half-up to 0.01 ft². Room totals and the project subtotal are the sums of those rounded lines, not a fresh round of the exact sum.
- Waste amount = the rounded subtotal × waste %, rounded half-up to 0.01 ft². Total with waste = subtotal + waste amount (so 10% of 184.00 is 18.40, and the total is 202.40).
A zero length, width, diameter, base or height is rejected for that dimension (“Enter a size greater than 0”) rather than shown as a finished 0.00 ft² answer.
Worked examples
Feet and inches (SF2).
12 ft 6 in × 10 ft 3 in is 12.5 ft × 10.25 ft = 128.125, shown as 128.13 ft².
A circular rug or round room (SF3).
A 10 ft diameter: exact area 78.539816…, shown as 78.54 ft².
A triangle (SF4).
Base 8 ft and height 6 ft: (8 × 6) ÷ 2 = 24.00 ft².
Two rooms plus 10% waste (SF5).
A 12 × 10 room is 120.00 ft². An 8 × 8 room is 64.00 ft². Subtotal: 184.00 ft². Waste at 10%: 18.40 ft². Total to order: 202.40 ft².
An L-shape as two rectangles, plus 5% waste (SF6).
16 ft × 12 ft = 192.00 ft². 8 ft × 6 ft 6 in = 8 × 6.5 = 52.00 ft². Subtotal: 244.00 ft². Waste at 5%: 12.20 ft². Total: 256.20 ft².
A larger circle in feet and inches (SF7).
A 12 ft 3 in diameter (12.25 ft): exact area 117.858811…, shown as 117.86 ft².
Inches only (SF8).
0 ft 18 in × 0 ft 18 in is 1.5 ft × 1.5 ft = 2.25 ft².
Common areas at a glance
| Shape | Size | Area |
|---|---|---|
| Rectangle | 12 ft × 10 ft | 120.00 ft² |
| Rectangle | 12 ft 6 in × 10 ft 3 in | 128.13 ft² |
| Circle | 10 ft diameter | 78.54 ft² |
| Circle | 12 ft 3 in diameter | 117.86 ft² |
| Triangle | 8 ft base × 6 ft height | 24.00 ft² |
| Two rooms, 10% waste | 12×10 + 8×8 | 202.40 ft² |
FAQ
How do I calculate square footage?
For a rectangle, multiply length by width, after converting every side to feet (inches ÷ 12). A 12 ft by 10 ft room is 120.00 ft². Add the rooms together for a whole floor.
How do I enter feet and inches?
Put feet in the feet box and leftover inches in the inches box. 12 ft 6 in is 12.5 ft. You can also leave feet at 0 and type the whole measurement in inches: 18 in is 1.5 ft.
How do I measure an L-shaped room?
Split it into two rectangles, measure each one and add them. The example of 16 × 12 plus 8 ft × 6 ft 6 in totals 244.00 ft² before waste.
How much extra should I add for waste?
It depends on the material and the layout. A simple room with straight plank flooring often needs less than a diagonal tile job. The 10% example on 184.00 ft² adds 18.40 ft², for 202.40 ft² to order. This page does not pick a waste percent for you.
How do I find the area of a circle?
Use the diameter. Area = π × (diameter ÷ 2)². A 10 ft circle is 78.54 ft²; a 12 ft 3 in circle is 117.86 ft².
Does this tell me how much paint, concrete or mulch to buy?
No. It stops at square footage (and optional waste). Use the paint, concrete, mulch and gravel, paver or deck calculators for gallons, bags and boards.
Why does 12 ft 6 in by 10 ft 3 in show 128.13 instead of 128.125?
Each displayed area is rounded half-up to the hundredth of a square foot. 128.125 becomes 128.13. Totals add those already-rounded lines, so a multi-room project matches what you see row by row.
Can I use square yards?
Yes — divide square feet by 9 if you want that view for material notes. The figures this page verifies and displays are in square feet.