Square Inches to Square Feet Calculator
Convert square inches (sq in) to square feet (sq ft) with the exact factor 1 sq ft = 144 sq in. Type either box — the converter runs in both directions.
Last updated:Conversion Formula
1 square foot = 144 square inches — so square feet = square inches ÷ 144, and square inches = square feet × 144.
Example: 2,880 sq in ÷ 144 = 20 sq ft. Conversion factors on this page follow NIST Special Publication 811.
Why the Divisor Is 144, Not 12
Everyone knows 12 inches in a foot, so the instinct is to divide by 12. That works for length and fails for area, because both directions of the measurement have to shrink:
- A square foot is a square 12 × 12 inches, so it holds 144 square inches — the inch-to-foot conversion happens twice, once per side.
- Take a 24 in × 36 in sheet: 24 × 36 = 864 sq in. Divide by 144 and it is 6 sq ft. Divide by 12 and you get 72, twelve times too large — and the check that catches it costs one second: 24 in = 2 ft, 36 in = 3 ft, and 2 × 3 = 6.
The general rule: converting a linear inch measurement divides by 12; converting a square inch measurement divides by 12² = 144. If your number came from multiplying two inches together, it needs the squared divisor.
Quick Reference Table
| Square Inches | Square Feet |
|---|---|
| 144 sq in | 1 sq ft |
| 432 sq in | 3 sq ft |
| 720 sq in | 5 sq ft |
| 1,440 sq in | 10 sq ft |
| 2,880 sq in | 20 sq ft |
| 4,320 sq in | 30 sq ft |
| 7,200 sq in | 50 sq ft |
| 14,400 sq in | 100 sq ft |
| 28,800 sq in | 200 sq ft |
| 43,200 sq in | 300 sq ft |
Pieces Per Square Foot
Material is bought by the square foot and laid by the piece, so the count you need is 144 ÷ (tile area in sq in). For whole-inch sizes that divide 144 evenly:
| Piece size (in) | Area (sq in) | Pieces per sq ft | Pieces for 10 sq ft |
|---|---|---|---|
| 12 × 12 | 144 | 1 | 10 |
| 6 × 6 | 36 | 4 | 40 |
| 4 × 4 | 16 | 9 | 90 |
| 3 × 6 | 18 | 8 | 80 |
| 2 × 2 | 4 | 36 | 360 |
These are coverage counts on the nominal face size. Real spacing adds grout joints — a 6 × 6 tile set with a 3/16 in joint covers a 6.1875 in square, so a grid count from the bare tile size under-orders by roughly 6% before any cut waste. Sizes that do not divide 144 evenly (a 5 × 5 tile is 25 sq in, 5.76 per sq ft) simply mean you compute by area and round the purchase up to whole boxes.
When the Tape Reads Feet and Inches
Room dimensions rarely arrive as clean square inches. Convert each side to inches first, multiply, then divide by 144 once:
- A niche 4 ft 6 in × 2 ft 6 in: that is 54 in × 30 in = 1,620 sq in, and 1,620 ÷ 144 = 11.25 sq ft.
- Same answer the shorter way: 4 ft 6 in = 4.5 ft, 2 ft 6 in = 2.5 ft, and 4.5 × 2.5 = 11.25 sq ft. The inches never enter it.
Use whichever path matches how you wrote the measurement down. The mistake to avoid is converting only one side — a 54 in × 2 ft rectangle multiplied straight through gives 108 of something that is neither unit.
Where This Conversion Shows Up
- Tile and backsplash work where the pieces are dimensioned in inches and the sell sheet quotes price per square foot.
- Duct, countertop, signage, and film surfaces specified in inches.
- Product specs — a 24 in × 36 in sheet is 864 sq in = 6 sq ft, which is what a "6 sq ft per pack" label is counting.
- Check the number is even: any square-inch figure that is a multiple of 144 converts to a whole square footage.
FAQ
How many square feet is 1,440 square inches?
10 sq ft. 1,440 ÷ 144 = 10, because a square foot is a 12 in × 12 in square holding 144 square inches.
How do I convert a 24 × 36 inch sheet to sq ft?
Multiply the sides for square inches: 24 × 36 = 864 sq in. Then divide by 144: 864 ÷ 144 = 6 sq ft. Don't divide 864 by 12 — that converts length, not area, and returns 72 instead of 6.
How many tiles fit in one square foot?
Divide 144 by the tile's area in square inches: 12 × 12 is 1 per sq ft, 6 × 6 is 4, 4 × 4 is 9, 3 × 6 is 8, and 2 × 2 is 36. Add grout joint and cut waste on top of that count.
Is there a shortcut for mental math?
Round 144 up to 150: divide by 150, then add about 4%. 1,500 sq in ÷ 150 = 10, plus 4% is 10.4 sq ft — the exact answer is 10.42.
Sources and How to Check This Page
- The divisor is definitional, not measured: 1 ft = 12 in exactly, so 1 sq ft = 12 × 12 = 144 sq in exactly. Every table entry above is that one multiplication.
- The inch-to-metre and foot definitions used by NIST's conversion tables are at NIST Special Publication 811; nothing on this page depends on a rounded factor.
- The grout-joint note is arithmetic on a 3/16 in joint (6.1875² = 38.29 sq in per set 6 × 6 tile, so 144 ÷ 38.29 = 3.76 per sq ft instead of 4). Bring your own tile spacing and re-run it.