This tile calculator works out how many tiles — and how many boxes — you need for a floor or wall. Enter the area, your tile size and grout gap, and it adds a breakage allowance so you do not run short one row from the end.
What Is a Tile Calculator?
A tile calculator converts a floor or wall area into a tile count, using the tile’s real installed size — tile plus its share of the grout joint — and a waste allowance for cuts and breakage. Tiles are sold by the box with awkward coverage figures, so buying “just enough” by square footage alone nearly always ends one box short. This tool is part of our Construction Calculators collection.
Worked Example (Verified)
A 10 ft × 12 ft bathroom floor (120 sq ft) with 12″ × 12″ tiles:
- Ignoring grout: each tile covers 1 sq ft → 120 tiles; with 10% waste: 132 tiles
- With a ¼″ grout gap, each tile effectively covers 1.042 sq ft → 127 tiles with waste (the calculator shows your exact figure for your gap)
- At 10 tiles per box: 14 boxes (for the no-gap estimate) — about $490 at $35/box
Measure the room carefully — odd shapes should be split into rectangles and added. Our Square Footage Calculator handles L-shaped areas, and the matching wall paint goes through the Paint Calculator.
How Much Waste Should You Add?
- 10% — straight grid layouts in simple rectangular rooms.
- 15% — diagonal (45°) layouts, large-format tiles, rooms with many cuts.
- 20% — herringbone and intricate patterns, or first-time tilers.
- Always keep a few leftover tiles from the same batch (dye lot) for future repairs — replacements years later rarely match.
Do Not Forget the Other Materials
- Thinset mortar: roughly one 50 lb bag per 60–80 sq ft with a standard notch trowel.
- Grout: a 10 lb bag covers roughly 100–200 sq ft depending on tile size and joint width — smaller tiles mean more joints and more grout.
- Backer board/underlayment for floors, and spacers matched to your grout gap.
- Outdoor slabs under the project? The Concrete Calculator does those quantities.
Related Tools
- Square Footage Calculator — irregular areas
- Paint Calculator — paint for the same room
- Concrete Calculator — slabs and footings
Frequently Asked Questions
How many tiles do I need for 100 square feet?
With 12×12 tiles, about 100 tiles before waste, 110 with 10% extra — enter your tile size and gap above for your exact count and box total.
Why does the grout gap change the count?
Each tile occupies its own size plus one grout joint in the layout. Wider gaps mean each tile covers more area, so you need slightly fewer tiles — but more grout.
How many tiles come in a box?
It varies by tile size — commonly 10–15 for 12×12 floor tiles, more for small mosaics. The box prints its coverage in square feet; match it in the “tiles per box” field.
Should I buy extra tiles?
Yes — the waste allowance in this calculator. Tiles break during cutting, and a cracked tile five years from now needs a same-batch spare.
Does this work for wall tiles and backsplashes?
Yes — enter the wall’s length and height as the “area” and the same math applies.
Is this tile calculator free?
Yes — free, instant, no sign-up.