Tile Calculator — ToolWitty
Free tool
Tile Calculator
Tiles, boxes, grout, and thinset for your floor or wall — with cutting waste built in.
1Project area
ft
ft
L-shaped rooms: split into rectangles, run each, and add the results.
2Tile & waste
10%
Enter your room size to calculate.
Breakdown
Boxes needed by tile size
For your area and waste level, using typical box counts:
Step-by-step math
Actual material needs vary with tile lot, layout pattern, subfloor condition, and installer technique. Always verify box coverage and grout coverage on the product labels, buy all tile from the same dye lot, and keep spare tiles for future repairs.
How it works
Tile is sold by the box, so total tiles ÷ tiles-per-box (rounded up to whole boxes) gives your shopping list. Grout and thinset scale with area, not tile count:
| Tile size | Grout coverage / 25 lb bag |
|---|---|
| 3×6 subway | ~45 sq ft |
| 4×4 | ~60 sq ft |
| 6×6 | ~90 sq ft |
| 12×12 | ~175 sq ft |
| 12×24 | ~200 sq ft |
| 18×18 and larger | ~225+ sq ft |
How much waste to add
10% — standard for straight-lay floors in simple rooms. 15% — diagonal layouts, herringbone, or rooms with many corners. 15–20% — complex patterns, niches, or inexperienced installers. Grout assumes 1/8 in joints with sanded grout; thinset assumes a 1/4 in square-notch trowel (~95 sq ft per 50 lb bag).
Related tools
Tile Calculator: How Many Tiles, Boxes, Grout & Thinset You Need
Running out of tile mid-project is a special kind of misery — dye lots change between production runs, and that “close enough” box from a different lot will never quite match. Ordering too much, on the other hand, means hundreds of dollars of tile gathering dust in the garage.
This free tile calculator gets the number right the first time. Enter your room dimensions and tile size, and instantly get the tile count (with waste built in), how many boxes to buy, plus grout and thinset mortar estimates — everything for one shopping trip, updating live as you type.
How to Use the Tile Calculator
Step 1 — Enter room dimensions
Measure length × width in feet (or meters). For L-shaped rooms, split them into rectangles, run the calculator for each, and add the results. For walls, measure each wall separately.
Step 2 — Choose your tile size
Pick from common presets — 12×12, 12×24, 18×18, 24×24, 6×6, 4×4, or 3×6 subway — or enter custom dimensions in inches for anything exotic (hexagons, arabesque, planks). The tile-layout diagram shows your floor plan with the tile grid overlaid.
Step 3 — Set the layout pattern and waste
Pick your layout: straight lay suggests 10% waste, diagonal and herringbone suggest 15%, complex rooms with many cuts suggest 20%. The slider stays yours to fine-tune.
Step 4 — Check tiles per box
Confirm the number on your product listing — it varies by manufacturer. The calculator recalculates the box count instantly. The comparison chart shows how many boxes each tile size needs for your room, which often settles the “big tile vs. small tile” debate.
What the Calculator Tells You
Tile count with waste
The core formula:
Tiles needed = (Room area ÷ One tile’s area) × (1 + Waste %) — rounded up
A 10×10 ft room (100 sq ft) with 12×12 in tile (1 sq ft each) at 10% waste needs exactly 110 tiles. You can’t buy a fraction of a tile, so the calculator always rounds up.
Boxes to buy
Tile is sold by the box, so total tiles ÷ tiles-per-box, rounded up to whole boxes. The calculator pre-fills typical box counts (15 for 12×12, 8 for 12×24, 80 for 3×6 subway) — adjust to match your product’s label.
Grout estimate
One 25 lb bag of sanded grout covers roughly 175 sq ft for 12×12 tile with 1/8 in joints. Smaller tiles have far more joints per square foot, so coverage drops sharply: a 3×6 subway tile backsplash can need 3–4× more grout per sq ft than large floor tile.
| Tile size | Approx. coverage per 25 lb bag |
|---|---|
| 3×6 subway | ~45 sq ft |
| 4×4 | ~60 sq ft |
| 6×6 | ~90 sq ft |
| 12×12 | ~175 sq ft |
| 12×24 | ~200 sq ft |
| 18×18 and larger | ~225+ sq ft |
Thinset mortar estimate
One 50 lb bag of thinset covers about 90–100 sq ft with a 1/4 in square-notch trowel — the standard for most floor tile. Large-format tile (12×24 and up) needs a 1/2 in trowel and back-buttering, which uses more mortar.
Worked Example
Tiling a 12×10 ft bathroom floor (120 sq ft) with 12×24 in tile, 8 tiles per box, 10% waste:
- Tile area = (12 × 24) ÷ 144 = 2 sq ft each
- Tiles = (120 ÷ 2) × 1.10 = 66 → 66 tiles
- Boxes = 66 ÷ 8 = 8.25 → 9 boxes (72 tiles)
- Grout = 132 ÷ 200 ≈ 1 bag (25 lb)
- Thinset = 132 ÷ 95 ≈ 2 bags (50 lb)
Total shopping list: 9 boxes of tile, 1 bag of grout, 2 bags of thinset. Done in one trip.
Pro Tips
- Buy everything from one dye lot. Check the lot/caliber numbers on every box before leaving the store. Mixed lots = visible shade bands across your floor.
- Keep 5–10% spare tiles after the job. Future repairs with matching tile are priceless; the calculator’s waste factor plus one extra box usually covers this.
- Dry-lay first. Lay out a row of tile with spacers before mixing thinset to check your cuts and centering — it takes 10 minutes and prevents disasters.
- Large-format tile needs flat floors. Tile 15 in or longer on any side needs the substrate flat within 1/8 in over 10 ft, plus back-buttering for full coverage.
- Grout joint size matters. Smaller joints (1/16 in) look modern but demand perfectly uniform tile; 1/8–3/16 in is more forgiving and standard for floors.
- Seal natural stone. Marble, travertine, and slate need sealing before and after grouting — porcelain and ceramic don’t.
Disclaimer
Estimates only — actual material needs vary with tile lot, layout pattern, subfloor condition, and installer technique. Always verify box coverage and grout coverage on the product labels, buy all tile from the same dye lot, and keep spare tiles for future repairs.