Tile Calculator
Find out how many tiles you need for a room, including the grout gap, a waste allowance for cuts and breakage, how many boxes to buy, and an estimated total cost.
Tiles Needed
130
117.5 tiles before waste allowance
Room Area
120.0 sq ft
Boxes Needed
13
Result
A 12 × 10 ft room (120.0 sq ft) tiled with 12" × 12" tiles (with a 0.125" gap) needs about 117.5 tiles before waste, or 130 tiles after adding 10% extra for cuts and breakage. That's 13 box(es) at 10 tiles per box.
What Does a Tile Calculator Do?
A tile calculator estimates how many tiles you need to cover a floor, wall, or roof, based on the area to cover, the size of each tile, and the gap left between tiles for grout (or overlap, for tiles like roofing shingles). It also adds a waste allowance for cuts, breakage, and pattern matching, since the raw "area ÷ tile size" number always undercounts what you actually need to buy.
Tiles Needed at Different Waste Allowances
The same room and tile size, showing how many tiles to order depending on how much extra you add for cuts, breakage, and layout complexity.
| Waste Allowance | Tiles to Order |
|---|---|
| 0% | 118 |
| 5% | 124 |
| 10% (current) | 130 |
| 15% | 136 |
| 20% | 142 |
How the Calculation Works
Each tile's real "footprint" on the floor includes its share of the grout line around it, not just its own physical size — that's why the gap is added to both the length and width before computing how much floor area one tile effectively covers. The exact tile count from this formula is then increased by your waste percentage and rounded up, since you can only buy whole tiles.
Grout Gaps and Overlaps
Floor and wall tiles are almost always installed with a small gap between them, typically ranging from about 1/16" for a tight, modern look up to 1/2" for a more traditional or rustic style — filled afterward with grout. Real tiles are rarely perfectly uniform in size, and gaps help absorb that variation as well as any minor expansion and contraction over time. Some materials work the opposite way — roofing tiles and wood siding are installed with an overlap instead of a gap, which this calculator supports by entering a negative gap value.
Tile Size, Material, and Layout Affect How Much You Need
Tile sizes range from small mosaic pieces under half an inch up to large-format slab tiles 24" × 48" or bigger. Larger tiles mean fewer grout lines and can make a room feel more spacious, but they generally produce more cut waste around room edges. Material matters too — ceramic and porcelain are the most cost-efficient and common choices, glass tile is popular for backsplashes, quarry tile is often chosen for slip resistance in kitchens and outdoor areas, and natural stone (marble, granite, slate) offers unique patterns at a premium price. Layout pattern changes material needs substantially too: a simple linear grid is the most material-efficient layout, while a running bond (brick-style offset) or herringbone pattern typically requires roughly 10% or more extra material due to the additional cuts each pattern demands — factor that into your waste percentage if you're planning one of these layouts.
Example — Your Current Inputs
A 12 × 10 ft room (120.0 sq ft) tiled with 12" × 12" tiles (with a 0.125" gap) needs about 117.5 tiles before waste, or 130 tiles after adding 10% extra for cuts and breakage. That's 13 box(es) at 10 tiles per box.
Additional Example — A Small Bathroom
A 6 ft × 8 ft bathroom (48 sq ft) tiled with 8" × 8" tiles and a 1/8" grout gap needs about 109 tiles before waste. Adding a 10% waste allowance for cuts around the toilet, tub, and doorway brings that up to 120 tiles — at 12 tiles per box, that's 10 boxes to buy.
About These Parameters
- Room Length & Width
- The dimensions of the area you're tiling, in feet. For irregular rooms, split the space into simple rectangular sections and total the tiles needed for each.
- Tile Length & Width
- The physical size of a single tile, in inches, as listed on the product packaging or spec sheet.
- Grout Gap
- The spacing left between tiles, typically 1/16" to 1/2". Use a negative value if your tiles overlap instead of leaving a gap (as with some roofing or siding tiles).
- Waste / Extra
- The percentage of extra tiles to order beyond the exact math, covering cuts around edges and fixtures, breakage, and future repairs. 10% is a reasonable default for a simple grid layout; complex patterns need more.
- Tiles per Box & Price per Tile
- Optional fields — fill these in to also get the number of boxes to buy and an estimated total material cost.
Frequently Asked Questions
How much extra tile should I buy?
10% extra is a common default for a straightforward grid layout. Complex patterns like herringbone or running bond typically need more — often 10-15% or higher — since more tiles get cut at odd angles. It's also worth keeping a few extra tiles on hand indefinitely for future repairs, since matching discontinued tile later can be difficult.
Why does grout gap size affect the number of tiles I need?
Every tile effectively "takes up" its own size plus its share of surrounding grout line. Larger gaps mean each tile covers slightly less usable floor area, so a bigger gap very slightly increases the number of tiles needed to cover the same room — though the effect is usually small compared to the waste allowance.
Should I round up or down when the math gives a fraction of a tile?
Always round up — you can't buy a fraction of a tile, and rounding down would leave you short. This calculator always rounds the final tile count up to the next whole number.
Does tile size affect installation cost?
Often yes — larger tiles are generally faster to install per square foot (fewer pieces, fewer grout lines) but can be heavier and more prone to cracking if the subfloor isn't perfectly flat, sometimes requiring extra floor prep. Smaller tiles and intricate patterns typically take more labor time per square foot.