Tile Calculator
Enter your room area, tile size, grout gap, and wastage allowance to find exactly how many tiles and boxes you need to order.
How It Works
The tile calculator accounts for grout gaps so you get an accurate count rather than simply dividing area by tile face size.
Effective tile size:
- Effective width = Tile width + Grout gap
- Effective height = Tile height + Grout gap
Area per tile (including grout) = Effective width × Effective height
Net tiles needed = Room area ÷ Area per tile (rounded up)
With wastage: Tiles needed = Net tiles × (1 + wastage % ÷ 100), rounded up.
Boxes: If you enter tiles per box, Boxes needed = ceil(Tiles with wastage ÷ Tiles per box).
Example: Room = 150 ft² (13.94 m²). Tile size 12 × 12 inches (1 ft × 1 ft). Grout gap 3/16 inch (≈ 0.016 ft). Effective tile area = 1.016 × 1.016 = 1.032 ft². Net tiles = 150 ÷ 1.032 = 145.3 → 146 tiles. With 10 % wastage: 161 tiles. If box contains 10 tiles: 17 boxes.
Wastage guidelines:
- Straight lay: 10 %
- Diagonal (45°): 15 %
- Complex patterns or herringbone: 15–20 %
- Irregularly shaped rooms: add extra 5 %
Frequently Asked Questions
How much wastage should I allow?
For a simple straight lay in a rectangular room, 10 % is standard. For diagonal or herringbone patterns, use 15 %. For complex rooms with lots of cuts around obstacles, add 15–20 %. It is always better to over-order — leftover tiles can be kept for future repairs, and tiles from different batches may not match in colour.
What grout gap should I use?
For floor tiles, 3/16 inch (4–5 mm) is typical. For wall tiles, 1/8 inch (3 mm) is common. Large format tiles (24 × 24 inch and above) often use 3/16 to 1/4 inch gaps. Rectified tiles (precision cut) can use gaps as small as 1/16 inch. Always follow the tile manufacturer's recommendation.
What tile patterns affect how many tiles I need?
A standard straight (grid) layout minimises cuts and waste. A diagonal (45°) layout increases waste by about 15 % because more cuts are needed at walls. A brick bond (offset) pattern is similar to straight. Herringbone and chevron patterns require 15–20 % more tiles because each tile must be cut precisely at angles.
Should I always order extra tiles?
Yes, always order at least one extra box beyond your calculated need. Tiles are manufactured in batches (called lots or shading lots), and even nominally identical tiles from different batches can differ slightly in colour or texture. Future repairs will be much easier if you have matching tiles in storage.
Can I use this calculator for wall tiles?
Yes. Enter the total wall area you want to tile (height × width of each wall section) as the room area. The tile size and grout gap logic is identical for floor and wall tiles. Remember to subtract door and window openings from your wall area.