Details
Type feet and inches like 12'6" or just 12.5. Everything is saved on this device, so your list is still here in the shop.
About the square footage calculator
Square footage is the first number you need for almost every home job: flooring, carpet, paint, tiles, a new lawn, or simply comparing the size of two apartments. This calculator works it out from your measurements, in square feet or square metres, and shows the other units too.
Real rooms are not always simple rectangles. Add as many areas as you like, pick a shape for each — rectangle, triangle or circle — and tick Subtract for parts that do not count, like a kitchen island or a built-in closet.
How to use it
- Choose Feet & inches or Metres & cm
- Measure the room and type the length and width — 12'6" and 12.5 both work
- For an L-shaped room, press Add another area and split it into two rectangles
- Tick Subtract for anything that should not be counted
- Add a price per sq ft (or m²) to see the cost of flooring or carpet
How to calculate square footage
| Shape | Formula | Example |
|---|---|---|
| Rectangle or square | length × width | 12 ft × 10 ft = 120 sq ft |
| Triangle | base × height ÷ 2 | 10 ft × 6 ft ÷ 2 = 30 sq ft |
| Circle | 3.1416 × diameter × diameter ÷ 4 | 10 ft across = 78.5 sq ft |
| L-shaped room | split into two rectangles and add | 12×10 + 6×5 = 150 sq ft |
Feet and inches: divide the inches by 12. So 12 ft 6 in is 12.5 ft, and 10 ft 3 in is 10.25 ft. You can type it either way — the calculator understands both.
Common room sizes
| Room | Square feet | Square metres |
|---|---|---|
| 10 × 10 ft | 100 sq ft | 9.3 m² |
| 10 × 12 ft | 120 sq ft | 11.1 m² |
| 12 × 12 ft | 144 sq ft | 13.4 m² |
| 12 × 14 ft | 168 sq ft | 15.6 m² |
| 14 × 16 ft | 224 sq ft | 20.8 m² |
| 16 × 20 ft | 320 sq ft | 29.7 m² |
| 20 × 20 ft | 400 sq ft | 37.2 m² |
Area units
| Unit | Equals |
|---|---|
| 1 square foot | 144 square inches = 0.0929 m² |
| 1 square yard | 9 square feet = 0.836 m² |
| 1 square metre | 10.764 square feet |
| 1 acre | 43,560 square feet = 4,047 m² |
| 1 hectare | 10,000 m² = 2.47 acres |
Carpet is often priced per square yard: divide the square feet by 9.
Tips for measuring
- Measure wall to wall at floor level, and round up to the next inch or centimetre.
- Measure twice — once along each side. Old rooms are rarely perfectly square.
- For flooring, add extra for cuts: about 10% (the Tile & Flooring Calculator does this for you).
- Doorways and closets: include the closet if the flooring goes into it.
Frequently asked questions
How do I calculate the square footage of a room?
Measure the length and the width in feet and multiply them. A room 12 feet long and 11 feet wide is 12 × 11 = 132 square feet. For odd shapes, split the room into rectangles and add them up.
How do I find the square footage of an L-shaped room?
Split the L into two rectangles. Measure each, work out each area, and add them. In the calculator, press Add another area for the second rectangle.
How do I calculate the square footage of a house?
Add up the area of every room, hallway and closet — or measure the outside walls of each floor and multiply. Official rules for listing a home's size differ by country and area (for example whether stairs and garages count), so for a sale or an appraisal, ask a local professional.
How do I convert square feet to square metres?
Multiply square feet by 0.0929, or divide by 10.764. 200 sq ft is about 18.6 m². The calculator shows both at once.
How many square feet is an acre?
One acre is 43,560 square feet — roughly a square 208 feet on each side. The calculator shows acres for big areas like a yard or a field.
Can I mix feet and inches?
Yes. Type 12'6", 12 ft 6 in or 12.5 — they all mean the same.
Good to know
- Your areas are saved in this browser for next time
- Press Copy the list to paste the result into a message or a note
- Nothing is sent anywhere — it all works in your browser
Related tools
- Tile & Flooring Calculator — tiles or boxes of flooring for the area
- Paint Calculator — gallons of paint for a room
- Mulch, Soil & Gravel Calculator — for garden beds
- Concrete Calculator — for a slab or patio
- Wallpaper Calculator — rolls for a room
- Unit Converter — feet, metres and more
