Square inches to square feet
Divide by 144. Exact, by definition.
Material estimate
Enter a figure in square inches.
You need to buy
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Worth knowing
What this assumes
A hundred and forty-four, not twelve
A foot is twelve inches, so a square foot is twelve inches by twelve inches — 144 square inches. Both dimensions change unit at once, which is why the factor is 12 × 12 and not 12.
Dividing by 12 converts one dimension and leaves the other in inches. The answer comes out twelve times too large, and because it is still a plausible-looking number it usually survives until somebody counts the boxes. It is the single error this conversion exists to catch.
Common tile sizes in square feet
| Tile | Square inches | Square feet | Tiles per 100 ft² |
|---|---|---|---|
| 4 × 4 in | 16 in² | 0.1111 ft² | 900 |
| 6 × 6 in | 36 in² | 0.25 ft² | 400 |
| 3 × 6 in subway | 18 in² | 0.125 ft² | 800 |
| 12 × 12 in | 144 in² | 1 ft² | 100 |
| 12 × 24 in | 288 in² | 2 ft² | 50 |
| 18 × 18 in | 324 in² | 2.25 ft² | 45 |
| 24 × 48 in large format | 1,152 in² | 8 ft² | 13 |
Exact conversions. The last column is before any waste allowance — the lay pattern decides that, not the tile, and the tile calculator applies the published factor.
Why tile sizes are so tidy
A 12 × 24 inch tile is 288 square inches, which is exactly two square feet. That is deliberate: large format tiles are dimensioned in whole inches that divide cleanly into a foot, so a box covers a round number and a floor lays out predictably. The awkward ones are the mosaics and the subway tiles, where a single piece is a fraction of a square foot and the box coverage is the number that matters.
Where this goes next
Once the tile is in square feet, the tile calculator turns a floor into a count with the published waste factor for your lay pattern, and the backsplash calculator does the same for the strip above a counter — counting outlets without deducting them. The mortar underneath comes off the thinset calculator, which reads the manufacturer's trowel chart, and the joints off the grout calculator. To measure an awkward room first, the square footage calculator adds up rectangles and circles.
Common questions
How many square inches are in a square foot?
A hundred and forty-four. A foot is twelve inches, so a square foot is 12 × 12 = 144 square inches. It is exact by definition and it never changes.
How do I convert square inches to square feet?
Divide by 144. A 12 by 24 inch tile is 288 square inches, which is 2 square feet exactly. The check worth doing is that the square-foot figure should always be far smaller — if it is not, you probably divided by 12.
Why 144 and not 12?
Because you are converting an area, and both of its dimensions change unit at once. Twelve inches becomes one foot in each direction, so the area factor is 12 × 12. Dividing by 12 converts only one dimension and leaves the answer twelve times too large — which is the error this conversion exists to catch.
What is a 12x24 tile in square feet?
Two square feet exactly: 12 × 24 = 288 square inches, and 288 ÷ 144 = 2. That tidiness is not an accident — large format tiles are dimensioned in whole inches that divide sensibly into a foot, which is why 12x24, 24x24 and 24x48 are such common sizes.
How do I get from a tile size to a tile count?
Divide the floor area by the tile area, then add for waste — which depends on the lay pattern rather than the tile. The last column of the table below gives tiles per 100 square feet before any waste, and the tile calculator does the whole job with the published waste factor for a straight, diagonal or herringbone lay.