Example 1
- Unit: feet
- 12 ft × 10 ft
120 sq ft
How many sq ft is a 12 by 10 ft room? 120 sq ft, because 12 × 10 = 120.
Square Footage Calculator
The calculator multiplies length by width. A 12 by 10 ft room is 120 sq ft. 15 by 12 ft is 180 sq ft. In metres, 5 by 4 is 20 m².
Waste and material price are on floor area. Unit conversion only: m² to square feet.
Result
Enter the room length and width. The area will appear here.
How it works
The calculator multiplies length by width. 12 ft times 10 ft is 120 sq ft. 15 ft times 12 ft is 180 sq ft.
In metres the same formula applies. 5 m times 4 m is 20 m². 3 m times 3 m is 9 m².
The second result line shows the same area in the other unit. 1 m² is 10.7639 sq ft. 20 m² is 215.278 sq ft. 120 sq ft is 11.148 m².
This is the clean rectangle. The calculator does not subtract openings and does not add waste or a price.
The calculator does not accept zero or negative numbers. A comma and a period give the same fraction.
Waste and material cost belong on the floor-area page. A bare m² to sq ft conversion belongs on the unit converter.
Formula
A = L × W; 1 m² = 10.7639 sq ft
Sides in feet give sq ft. Sides in metres give m². The other unit uses 1 m² = 10.7639 sq ft.
How to use
- Keep feet if you measured the room in feet.
- Enter 12 and 10. The result is 120 sq ft.
- Enter 15 and 12. The result is 180 sq ft.
- In metres enter 5 and 4. The result is 20 m², or 215.278 sq ft.
120 sq ft from 12 × 10 ft
Rectangle area is length times width. 12 × 10 ft is 120 sq ft.
- P
- Area. 5 × 4 m = 20 m². 12 × 10 ft = 120 sq ft.
- m²
- Square metre. 1 m² = 10.7639 sq ft. 20 m² = 215.278 sq ft.
- sq ft
- Square foot. 120 sq ft = 11.148 m². This is not an acre.
Examples
Example 2
- Unit: feet
- 15 ft × 12 ft
180 sq ft
How many sq ft is 15 by 12 ft? 180 sq ft.
Example 3
- Unit: metres
- 5 m × 4 m
20 m²
How many m² is a 5 by 4 m room? 20 m², or 215.278 sq ft.
Related calculators
Frequently asked questions
How many sq ft is a 12 by 10 ft room?
120 sq ft. 12 × 10 = 120. That is the clean rectangle, without waste.
How many sq ft is 15 by 12 ft?
180 sq ft.
How many m² is a 5 by 4 m room?
20 m², which is 215.278 sq ft.
How many sq ft is 20 m²?
215.278 sq ft. 1 m² is 10.7639 sq ft.
Is 8% waste in the result?
No. Waste and price belong on the floor-area page.
Is a window opening subtracted from the area?
No. This page counts the rectangle only. Openings belong on floor area.
Can I enter 400 cm as 400?
No, if the unit is metres. 400 cm is 4 m. Entering 400 would be a 400 m side.
How is this different from m² to sq ft?
That page starts from an area you already have. This page starts from two sides.
Are negative numbers accepted?
No. Zero is not accepted either. Sides must be greater than zero.
Do a comma and a period both work?
Yes. 4,5 and 4.5 give the same fraction.
Sources
Rectangle area is the product of the sides. 1 m² is 10.7639 sq ft.
Page updated in 2026.