Dividing room area by tile area seems like the obvious calculation — until you remember that tiles don't sit flush against each other. Every tile actually claims its own size plus a grout line on each side.
Tile calculator with grout, not just room ÷ tile
A 12" × 12" tile with 1/8" grout spacing actually occupies about 12.125" × 12.125" of floor once it's installed with its grout line. Over a 100 sq ft room, that difference is enough to change how many tiles round up to the next full box.
How many tiles do I need, plus a waste factor
Enter your room dimensions, tile dimensions, and grout spacing, and this calculator computes the real per-tile coverage first, then applies your waste factor (10% is typical, more for diagonal layouts or lots of cuts) before rounding up to a whole tile count.
Tile boxes calculator, so you know what to actually buy
Enter how many tiles come in a box and the tool converts your tile count straight into the number of boxes to purchase — no separate division step.
