🧱 Tile & Flooring Calculator
Enter your room dimensions and tile size to find how many tiles to buy, including a waste allowance for cuts and breakage.
How the tile count is worked out
The tile's two dimensions are in inches, so their product is divided by 144 to get the area of one tile in square feet. The room area divided by that gives the exact count, the waste allowance is added, and the result is rounded up - then rounded up again to whole boxes if you enter a box size.
room area = length x width
tile area = (tile width x tile length) / 144
tiles = ceiling(room area / tile area x (1 + waste% / 100))
boxes = ceiling(tiles / tiles per box)A 12 x 10 ft room is 120 sq ft. In 12 x 12 in tiles that is 120 tiles exactly, 132 with the 10% allowance, and 14 boxes of ten - which is 140 tiles, eight more than the calculation asked for.
Choosing the waste percentage
The allowance is doing real work here. Every tile that meets a wall gets cut, and the offcut only helps if the opposite wall happens to need the same sliver:
| Layout | Allow |
|---|---|
| Straight, square room, small tiles | 10% |
| Diagonal, or a room with alcoves and doorways | 15% |
| Herringbone, or large-format tiles | 20% |
Large formats waste more than small ones for the same room, because the piece you cut off a 24 in tile is a 24 in offcut. Natural stone deserves more again: it varies in colour and pattern, so tiles get set aside and re-sorted rather than laid in the order they come out of the crate.
- Mix boxes as you lay. Shade varies between production runs, and even within a batch. Open three or four boxes and work from all of them so any variation is spread across the floor instead of arriving as a stripe.
- Check the batch or dye lot number before you leave the shop, and buy the whole job at once - the same product bought six months later is a different run.
- Keep the spare tiles. Those eight extras from the last box are the only exact match you will ever have for a cracked tile.
Frequently asked questions
How many 12x12 tiles do I need for a 12x10 room?
120 sq ft means 120 tiles before waste, 132 with a 10% allowance. If they come ten to a box, that is 14 boxes.
How much extra tile should I buy?
10% for a straightforward square room, 15% for a diagonal layout or a room with alcoves and doorways, and 20% for herringbone or large-format tiles. The driver is how many tiles end up cut, not the floor area.
Why do my tiles look slightly different shades?
Because they came from different production batches, or different points in the same one. It is normal for ceramic and unavoidable in stone. The fix is to open several boxes and mix as you lay, not to hunt for a perfect match.