Bathroom Tile Calculator — Tiles, Waterproofing & Adhesive
Calculate exactly how many tiles, how much waterproofing membrane, wet-area adhesive and grout you need for a bathroom renovation. Handles floors, walls and shower enclosures with appropriate waste factors for each surface.
How the bathroom tile calculator works
- 1Calculate floor area and wall area separately (m²)
- 2Apply 10% waste for straight-lay floor tiles, 15% for wall tiles with cuts around fixtures
- 3Waterproof membrane: total wet-area m² × coverage rate (typically 0.8–1.0 kg/m² per coat, 2 coats)
- 4Wet-area adhesive (C2 S1/S2): area × 4.5–5.5 kg/m² depending on tile size
- 5Grout: calculated from tile perimeter, joint width, tile thickness and grout density
- 6Round all quantities up to nearest pack or bag
Worked example
Bathroom: 2.1 m × 2.4 m floor (5.04 m²), four walls totalling 22 m², 300×600 mm wall tiles, 300×300 mm floor tiles (0.09 m² each).
Floor: 5.04 ÷ 0.09 = 56 tiles × 1.10 waste = 62 tiles. Walls: 22 ÷ 0.18 = 122 tiles × 1.15 waste = 141 tiles. Adhesive: ~140 kg. Waterproof membrane: ~40 kg (2 coats).
Frequently asked questions
What adhesive should I use for bathroom tiles?
Use a C2 S1 flexible adhesive in standard bathroom areas and C2 S2 (highly deformable) in shower enclosures and heated floors. Standard C1 adhesive is not suitable for wet areas.
Do I need waterproofing membrane under bathroom tiles?
Yes — all areas with direct water contact (shower, bath surround, floor near drain) require a tanking membrane or liquid waterproofing before tiling. EN 14891 / TEK17 require W2-I classification in wet zones.
How much extra tile for a bathroom?
Add 10% for floor tiles on straight lay, 15% for wall tiles (more cuts around windows, pipes and fixtures). Always buy one spare box in the same dye lot — tiles can crack during drilling or later use.
What grout joint width for bathroom tiles?
2–3 mm for rectified tiles laid close together. 3–5 mm for standard bathroom tiles. Use a CG2 W (water-resistant) grout in all wet areas — standard CG1 grout is not appropriate for shower enclosures.
How long does bathroom tiling take?
A professional tiler typically completes 8–12 m² of wall tiling per day. Allow 24–48 hours for adhesive to cure before grouting, and 7 days before exposing to standing water.