Feet and Inches Area Calculator
Press Calculate to see the area, the working and other units.
Multiply a length by a width when both are measured in feet and inches, without converting anything by hand. You get square feet, square inches, square yards and square meters.
A tape measure gives you feet and inches, but square footage needs a single number for each side. That small step is where most hand calculations go wrong, because an inch is a twelfth of a foot and not a tenth. Enter each side as you read it off the tape, and the conversion is handled for you.
Formula
A = (l ft + l in ÷ 12) × (w ft + w in ÷ 12)
- A
- the area in square feet
- l ft, l in
- the feet and inches of the length
- w ft, w in
- the feet and inches of the width
How the calculation works
Divide the inches by 12, add them to the feet, and multiply the two sides. For a room of 12 ft 6 in by 10 ft 3 in, the sides become 12.5 ft and 10.25 ft, and 12.5 × 10.25 = 128.125 ft². That is 18,450 square inches, about 14.24 square yards or about 11.90 square meters.
You can also work entirely in inches. The same room is 150 in by 123 in, or 18,450 square inches, and dividing by 144 gives 128.125 ft² again.
- Square inches = square feet × 144
- Square yards = square feet ÷ 9
- Square meters = square feet × 0.092903
The decimal trap
It is tempting to write 12 ft 6 in as 12.6 and 10 ft 3 in as 10.3. Those are different lengths. Multiplying them gives 129.78 ft², about 1.7 ft² too high on a single small room. The error grows with the number of inches. Nine inches is 0.75 of a foot, not 0.9. Use this table if you are working on paper.
| Inches | Decimal feet |
|---|---|
| 1 | 0.083 |
| 2 | 0.167 |
| 3 | 0.25 |
| 4 | 0.333 |
| 5 | 0.417 |
| 6 | 0.5 |
| 7 | 0.583 |
| 8 | 0.667 |
| 9 | 0.75 |
| 10 | 0.833 |
| 11 | 0.917 |
Reading the result
Decimals in an area are parts of a square foot, not inches. The 0.125 in 128.125 ft² is one eighth of a square foot, which is 18 square inches. It does not mean 1 inch or 12.5 inches, so 128.125 ft² should never be read as 128 feet 1 inch.
Fractions of an inch work too, typed as decimals. Enter 4½ in as 4.5 and 7¼ in as 7.25. A shelf of 3 ft 4½ in by 2 ft 7¼ in comes to about 8.79 ft². If the inches box holds 12 or more, the extra simply counts toward the feet, so 5 ft 14 in is treated as 6 ft 2 in.
Rooms and larger jobs
For a room that is not a plain rectangle, split it into rectangles, run each one and add the square feet. A room of 9 ft 8 in by 11 ft 4 in comes to about 109.56 ft², and a closet of 3 ft 2 in by 2 ft 6 in adds about 7.92 ft², for about 117.47 ft² in all. Flooring is usually priced by the square foot and carpet often by the square yard, so the calculator lists both. For metric measurements, the square meter area calculator is the better fit.
Frequently asked questions
How do I calculate square feet from feet and inches?
Divide the inches by 12 and add them to the feet for each side, then multiply the two sides. 10 ft 6 in by 12 ft is 10.5 × 12 = 126 square feet.
How many square inches are in a square foot?
There are 144, because a square foot is 12 inches by 12 inches. To convert square inches to square feet, divide by 144.
How do I convert square feet to square yards?
Divide by 9, because a yard is 3 feet and 3 × 3 = 9. An area of 128.125 ft² is about 14.24 square yards.
What if a side is an exact number of feet?
Enter 0 in the inches box, or leave it blank. A side of 10 ft 0 in is simply 10 feet.
What if a side is under one foot?
Enter 0 for the feet and the measurement in the inches box. A strip of 8 in by 6 ft is 0.667 × 6 = 4 square feet.
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