Wall and Backsplash Tile Calculator
Works out wall or splashback tiles from the area, with openings deducted and the adhesive included.
Includes the waste allowance — this is the figure to order.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
units per m² = 1,000,000 ÷ ((face length + joint) × (face height + joint)) units = area × units per m² × (1 + waste)
Each unit effectively occupies its own face plus one joint along two edges, because the joint is shared with its neighbour. Working from the real face size and adding the joint is the only reliable way — nominal sizes already include the joint, so adding one again counts it twice.
What to watch out for
Wall tiling is more about setting out than quantity:
- Start from the centre. Working from a corner leaves a sliver at the far end. Centring means the cuts at both ends match and look deliberate.
- Showers need tanking. Tile and grout are not waterproof. A wet area needs a tanking membrane behind the tiles and a cement-based adhesive.
- Deduct the big openings only. A window is worth taking off; a socket is not — you cut the tile around it and the offcut is scrap anyway.
Frequently Asked Questions
How many tiles for a kitchen splashback?
A 3 m run 600 mm high is 1.8 m². In 200 × 100 mm metro tiles with 2 mm joints that is about 88 tiles, or 97 with 10% waste.
How much adhesive for wall tiles?
About 1.5 kg per square metre per millimetre of bed, so a 4 mm bed is roughly 6 kg/m². A 20 kg bag covers a little over 3 m².
Do I need to waterproof behind shower tiles?
Yes. Grout is not waterproof and tiles are only as good as what is behind them. A shower enclosure needs a tanking membrane or waterproof backer board, with cement-based adhesive rather than ready-mixed.