How to use this calculator
- Choose an area input mode. Dimensions builds the area from length × width — a floor, a backsplash, an accent wall. Total area lets you enter a known area from a plan or take-off directly. Both modes have an optional area to subtract for vanities, cabinets, or fixtures you will tile around.
- Pick your tile size. Common imperial and metric sizes are preloaded; edit the dimensions for a custom tile. Sizes are nominal — the spec sheet is authoritative.
- Set waste and packaging. 10% covers straight cuts in simple rooms; diagonal and herringbone layouts need more. Enter a tiles-per-box count to buy whole boxes, or leave it empty for individually sold tiles.
- Add a price — per tile or per box, whichever matches how you are buying — for an estimated total.
The formula
Net area is the surface area minus what you subtract. Tile coverage is tile width × tile height — 1 sq ft for a 12 × 12 in tile. When a tiles-per-box count is given, boxes = tiles ÷ tiles per box, rounded up to whole boxes. The only rounding is the final round-up; no intermediate rounding is applied.
Worked example
A 10 × 8 ft kitchen floor, nothing subtracted, 12 × 12 in tiles, 10% waste, at $2.50 per tile:
| Step | Result |
|---|---|
| Area: 10 × 8 | 80 sq ft |
| Required with waste: 80 × 1.10 | 88 sq ft |
| Tile coverage: 1 × 1 ft | 1 sq ft per tile |
| Tiles: 88 ÷ 1 = 88 → round up | 88 tiles ≈ $220 |
If that product ships 10 tiles per box, enter 10 in "tiles per box": 88 ÷ 10 = 8.8 → buy 9 boxes. If the box price is $24, the estimated total is $216.
Why tile waste runs higher than you might expect
Every edge tile is cut, and cut tiles rarely fit anywhere else. Handling breaks a few, and pattern layouts — diagonal, herringbone, large-format brick joints — turn even more tiles into offcuts. That is why the waste field starts at 10% and is yours to raise: the calculator shows its work, but only you know your room's corners and your layout.
Common mistakes
- Trusting nominal sizes — a "12-inch" tile is not always 12.000 inches. Enter actual dimensions when they differ.
- Ordering from mixed production lots — color can vary between lots of the same product. Buy everything at once, including your spares.
- Setting 0% waste because the math looks exact — cuts and breakage are certain; the only question is how much.
- Subtracting baseboards and edges you plan to tile up to — subtract only what you will genuinely tile around.
- Forgetting that the estimate covers tile only — thin-set, grout, backer board, spacers, and trim are separate purchases.
For showers, tub surrounds, and other wet areas, waterproofing, substrate preparation, and slip-resistance requirements follow your local building code — this calculator estimates tile quantities only.
FAQ
How many 12 × 12 tiles do I need for a 10 × 10 room?
The room is 100 sq ft; with a 10% allowance that is 110 sq ft. A 12 × 12 in tile covers exactly 1 sq ft, so 110 tiles — the calculator rounds up from 110 exactly. If you buy by the box, enter the tiles-per-box count and it will round up to whole boxes instead.
Why does tile waste run higher than paint?
Every tile is cut to fit edges and obstacles, and cut tiles are rarely reusable. Breakage during handling and installation adds more. Straight layouts in simple rooms are usually fine at 10%; diagonal, herringbone, or brick-joint patterns and rooms with many jogs can need 15–20%.
Are nominal tile sizes the real tile size?
Not always. A "12-inch" tile may measure slightly differently, and metric and imperial products are rarely identical. The coverage difference is small per tile but real over a large floor — check the actual dimensions on the product spec sheet and enter those if they differ.
Does the estimate include grout and adhesive?
No. The calculator estimates tiles only. Thin-set, grout, backer board or membrane, spacers, and trim pieces are separate purchases with their own coverage rules. For wet areas like showers, waterproofing follows your local building code.