Free tile calculator
Enter your room area and tile size — this tile calculator returns tiles needed, boxes to buy, and total cost with your chosen waste factor for straight or diagonal installation, updated live, as you type.
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Standard waste: 10% straight lay, 15% diagonal. Buy one extra box for future repairs.
Results are estimates. Consult a professional.
How the tile calculator works
Tile area and room area are measured in different units — tiles in square inches, rooms in square feet — so the calculation begins with a unit conversion. The calculator finds each tile's area in square inches, converts room area to square inches, divides to get the base tile count, adds a waste percentage for cuts and breakage, then divides by tiles per box to produce the box count you need to order.
Worked example: 12×12 tiles in a bathroom
A homeowner is tiling a 10 ft × 12 ft bathroom floor with 12×12 inch porcelain tiles in a straight lay pattern. He is using 10% waste (standard for a straight set) and his tiles come 15 per box. He needs to know how many tiles and boxes to order.
Tiles needed per 100 sq ft by tile size
This table shows how many tiles are needed per 100 sq ft of floor area at 10% and 15% waste for common residential tile sizes. Scale proportionally for other room sizes. Use 10% waste for straight lay, 15% for diagonal or offset patterns, and 20% for herringbone or basket weave.
| Tile size | Base tiles / 100 sq ft | With 10% waste | With 15% waste |
|---|---|---|---|
| 4 × 4 in | 900 | 990 | 1,035 |
| 6 × 6 in | 400 | 440 | 460 |
| 12 × 12 in | 100 | 110 | 115 |
| 12 × 24 in | 50 | 55 | 58 |
| 18 × 18 in | 45 | 50 | 52 |
| 24 × 24 in | 25 | 28 | 29 |
Counts ceiling-rounded to the next whole tile. Source: TCNA installation standards; 1 ft² = 144 in².
Tips for ordering and laying tile
Tile quantities are easier to get wrong than most materials because nominal size, actual size, grout joint width, and lay pattern all interact. These five tips prevent the most common ordering and layout mistakes.
- Always buy from a single dye lot — tile color and surface texture vary between production batches even from the same manufacturer. Every carton carries a dye lot number; match all cartons at time of purchase. Running short and ordering a second delivery from a different lot is a visible mismatch you cannot fix.
- Order one extra box beyond your calculated count — keep it sealed and store it for future repairs. Tile patterns are frequently discontinued within a few years of installation. One spare box of the same dye lot can save an otherwise impossible match.
- Match your waste factor to your lay pattern — straight set: 10%; diagonal (45°) set: 15%; herringbone or basket weave: 20%. Diagonal patterns generate large corner triangles that look small but add up to significant material loss across an entire room.
- Subtract fixed obstacles before entering room dimensions — built-in cabinet bases, tub alcoves, and permanent fixtures that will not be tiled should be subtracted from the room area. Over-ordering slightly is fine; dramatically over-ordering wastes money on tiles you will never use.
- Grout joint width affects mortar and grout quantities, not tile count — wider joints (3/16 in or more) accommodate slight variation in non-rectified tile. Rectified tiles can use joints as narrow as 1/16 in. Either way, the tile count formula is unchanged; only grout volume changes with joint width.
Accuracy and limitations
The calculation assumes tiles of uniform actual size. Nominal tile sizes (12×12, 18×18) often differ from measured dimensions — a tile marketed as 12×12 may measure 11.75×11.75 inches. For large orders, measure an actual tile and enter those dimensions rather than the nominal size. The per-tile difference is small, but it compounds over hundreds of pieces and can shift your box count.
This calculator covers rectangular rooms. For L-shaped floors, bathrooms with alcoves, or areas that wrap around islands, split the space into rectangles, calculate tile count for each section separately, and add them together. The waste factor covers standard cut-and-fit losses; unusually intricate patterns or floors with many obstacles may warrant increasing waste to 20%. This tool does not estimate grout, mortar, backer board, waterproofing membrane, or transition strips — consult the TCNA handbook for full system specifications.
Tile installation terms defined
About this tile calculator
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