Tile Grout Calculator
Joint length from tile size, then cartridges.
Inputs
Result
Formula
| Joint per m² = 1/length + 1/width | in metres |
| Volume = length × width × depth | ÷1000 for ml |
| Cartridges = ceil(volume × (1+waste) ÷ pack) |
50 m² of 600×600 tiles, 2 mm joints 4 mm deep, 400 ml cartridges, 10% waste: 3.33 m of joint per m², 166.7 m total, 1333 ml growing to 1467 ml with waste, so 4 cartridges.
FAQ
Why do small tiles use so much more grout?
Total joint length is inversely proportional to tile size. 600×600 gives 3.33 m per m²; 300×300 doubles it to 6.67; mosaic at 50×50 has 40 m per m², twelve times as much. Small and rustic tiles therefore cost far more to grout - quote by tile size.
Epoxy grout or cementitious grout?
Cementitious is cheap and quick but absorbs water, stains and moulds - ugly after a few years in bathrooms and on floors. Epoxy does not absorb, resists staining, holds colour and can be scrubbed, at five to ten times the price and with exacting site requirements (clean, dry, even depth). A common split is epoxy in bathrooms and living areas, cementitious elsewhere.
Why does the tiler say four cartridges are not enough?
Usually three reasons: joints deeper than assumed (hollows behind tiles, over-cleaned joints); extra use at internal corners, drains and thresholds; and rework plus cleaning waste. Add 20-30% and hold depth at 3-4 mm. Mixed two-part grout cannot be kept, so plan whole cartridges for small areas.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.