# Tile Calculator: How Many Tiles & Boxes?

> Calculate the number of tiles, boxes, grout and thinset mortar you need for a floor, wall, shower or backsplash.

**Quick answer:** A 10 × 10 ft floor tiled with 12×12 in tiles needs about 108 tiles: 100 sq ft ÷ 1.02 sq ft per tile (with a 1/8 in grout joint) plus 10% waste. Formula: area × 144 ÷ ((tile width + joint) × (tile length + joint)) × 1.10.

_Last updated: October 3, 2026. Estimates only; confirm quantities with your supplier._

## How to calculate how many tiles you need

Divide the area to be tiled by the area one tile occupies (including its grout joint), then add a waste allowance for cuts and breakage.

```
tiles per sq ft = 144 ÷ ((tile width + joint) × (tile length + joint))
tiles = area × tiles per sq ft × (1 + waste %)
```

### Tiles per square foot by tile size

| Tile size | Tiles per sq ft (1/8 in joint) | Tiles for 100 sq ft (+10%) |
| --- | --- | --- |
| 4 × 4 in | 8.46 | 931 |
| 6 × 6 in | 3.84 | 423 |
| 3 × 6 in | 7.52 | 828 |
| 12 × 12 in | 0.98 | 108 |
| 12 × 24 in | 0.49 | 55 |
| 16 × 16 in | 0.55 | 61 |
| 18 × 18 in | 0.44 | 49 |
| 24 × 24 in | 0.25 | 28 |

### Waste by layout

| Layout | Suggested waste |
| --- | --- |
| Straight lay, rectangular room | 7–10% |
| Diagonal | 15% |
| Herringbone or complex patterns | 20% |
| Large-format tile (24 in+) | 15% |
| Small mosaic sheets | 5–10% |

### Estimating grout

Grout depends on the joint width, tile size and tile thickness. The calculator uses: area × (L + W) ÷ (L × W) × joint width × tile thickness × 10.5, where 10.5 combines the 144 square inches in a square foot, a grout density near 110 lb/ft³ and roughly 15% waste. Buy a little extra — color can vary between batches.

### Don't forget the rest of the job

Thinset mortar, backer board or uncoupling membrane, spacers, sealer and trim pieces all add to the list. For the other floor coverings, see the [flooring calculator](../flooring-calculator/) and [carpet calculator](../carpet-calculator/); for the measurements themselves, try the [square footage calculator](../square-footage-calculator/).

## Frequently asked questions

### How many 12×12 tiles do I need per square foot?

A 12 × 12 tile covers one square foot, but with a 1/8 in grout joint each tile occupies slightly more, so you need about 0.98 tiles per square foot before waste.

### How much extra tile should I buy?

Ten percent for simple layouts, 15–20% for diagonal, herringbone or large-format tile. Keep a few spares for repairs.

### How many tiles do I need for a 10×10 room?

A 10×10 room is 100 square feet — about 108 12×12 tiles at 10% waste, or 9–10 boxes of 11.

### How much grout do I need?

For 12×12 tile with a 1/8 in joint and 3/8 in tile it is roughly 0.08 lb per square foot; smaller tile, wider joints and thicker tile need more.

### How do I calculate tile for a backsplash?

Multiply the backsplash length by its height (usually 18 inches = 1.5 ft), subtract outlets and windows, and add 10% waste.

### How do I calculate tile for a shower?

Add the area of each wall (width × height), subtract the door or niche openings, then add 10–15% waste.

### Do I include the grout joint in tile size?

Yes — the formula adds the joint to both tile dimensions, because grout takes up space between tiles.

### How many boxes of tile do I need?

Divide the tiles needed by tiles per box and round up. Check the box label — many boxes list coverage in square feet rather than tile count.

## Sources and further reading

- [Tile Council of North America](https://www.tcnatile.com/) — TCNA: tile installation standards