Inches to Sqft Calculator
Measured in inches? Set the units below to inches, or to feet + inches, and the conversion happens automatically.
To convert inches to square feet, multiply the two inch measurements together and divide by 144. A surface 30 in × 48 in is (30 × 48) ÷ 144 = 10 square feet. The divisor is 144, not 12, because a square foot is 12 in × 12 in.
Formula: (Length in × Width in) ÷ 144
Formula: π × d² ÷ 4 ÷ 144
Formula: (b × h ÷ 2) ÷ 144
Why you divide by 144, not 12
This is the single most common square footage mistake. A foot is 12 inches, so it feels natural to divide by 12 — but you are converting area, not length.
One square foot is a square measuring 12 inches on each side. Its area is 12 × 12 = 144 square inches. So to go from square inches to square feet you divide by 144.
Dividing by 12 instead gives an answer twelve times too large, which is usually obvious once you sanity-check it: a 12 in × 12 in tile is exactly 1 square foot, not 12.
Two methods that both work
Method 1 — convert first. Divide each measurement by 12 to get feet, then multiply. For 30 in × 48 in: 30 ÷ 12 = 2.5 ft, 48 ÷ 12 = 4 ft, and 2.5 × 4 = 10 sq ft.
Method 2 — convert last. Multiply the inches together, then divide by 144. For the same surface: 30 × 48 = 1,440 in², and 1,440 ÷ 144 = 10 sq ft.
Method 2 involves fewer rounding steps, so it is slightly more accurate when your measurements are awkward numbers. Both are correct.
Working in feet and inches
Tape measures read in feet and inches, so most real measurements look like "12 ft 7 in". Convert the inches to a decimal by dividing by 12, then add:
- 12 ft 7 in → 7 ÷ 12 = 0.583 → 12.583 ft
- 8 ft 3 in → 3 ÷ 12 = 0.25 → 8.25 ft
- 12.583 × 8.25 = 103.81 sq ft
Select Feet + inches in the calculator above and it will do this for you — enter the feet in the first box and the inches in the second.
Common inch measurements in square feet
| Measurement | Square inches | Square feet |
|---|---|---|
| 12 in × 12 in | 144 in² | 1 sq ft |
| 24 in × 24 in | 576 in² | 4 sq ft |
| 30 in × 48 in | 1,440 in² | 10 sq ft |
| 36 in × 60 in | 2,160 in² | 15 sq ft |
| 48 in × 96 in | 4,608 in² | 32 sq ft |
| 18 in × 18 in | 324 in² | 2.25 sq ft |
| 6 in × 24 in | 144 in² | 1 sq ft |
Frequently asked questions
How do I convert inches to square feet?
Multiply the two inch measurements together to get square inches, then divide by 144. For example, 30 in × 48 in = 1,440 square inches, and 1,440 ÷ 144 = 10 square feet.
How many square inches are in a square foot?
There are 144 square inches in one square foot, because a square foot measures 12 inches by 12 inches and 12 × 12 = 144.
Why can I not just divide by 12?
Dividing by 12 converts length, not area. Because both dimensions are being converted, you divide by 12 twice — which is the same as dividing once by 144. Using 12 gives an answer twelve times too big.
How do I calculate square feet from feet and inches?
Convert the inches portion to a decimal by dividing by 12, add it to the feet, then multiply the two dimensions. 12 ft 6 in becomes 12.5 ft; 10 ft 3 in becomes 10.25 ft; 12.5 × 10.25 = 128.13 square feet.
How many square feet is a 12x12 tile?
A 12 inch by 12 inch tile is exactly 1 square foot. A 24 × 24 inch tile is 4 square feet, and an 18 × 18 inch tile is 2.25 square feet.