Tile Grout Calculator
Joint length from tile size, then cartridges.
Quick answer
With the default inputs: Tiled area 50 m² · Tile length 600 · Tile width 600 etc.Cartridges to buy 4 cartridges
Edit the inputs below to recalculate.Inputs
Result
Cartridges to buy
4cartridges
| Joint length per m² | 3.33m/m² |
| Total joint length | 166.7m |
| Net volume | 1.33L |
| Volume incl. waste | 1.47L |
| Metres per cartridge | 50.0m |
| Cartridges per m² | 0.080cartridges/m² |
Joint length per m² = 1/tile length + 1/tile width (in metres), derived from each tile contributing one long and one short joint. Smaller tiles mean more joint and more material. Depth dominates consumption - 2 mm versus 4 mm doubles the quantity - so joints are cleaned and backer foam inserted to control depth. Two-part epoxy must be used within 30-40 minutes of mixing, so buy in batches.
Reverse: known result, work out one input
Enter a target result; the other inputs stay fixed and this one is worked out.
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.
How to work it out
- Compute joint length first: area × (1/tile length + 1/tile width). At 600×600 that is 3.33 m per m²; at 300×600 it is 5 m, so smaller tiles mean far more joint.
- Multiply by joint width and sealant depth for the volume. Grout fills 3-5 mm, not the tile thickness — a 10 mm tile still only needs the surface few millimetres.
- Convert to cartridges: volume in ml ÷ cartridge content, rounded up.
- Add 10-15% waste for mixing-tube retention, edges and rework; allow more for matte or dark grouts.
- Count masking tape separately: about 2 m of tape per metre of joint, one strip each side.
Where it goes wrong
- Estimating by area, say one cartridge per 5 m² — at the same area, 300×300 tiles have more than twice the joint length of 800×800 and the estimate collapses.
- Using tile thickness as the depth — a 10 mm tile costed at 10 mm depth trebles the quantity, when only 3-5 mm is filled.
- Grouting straight after tiling — the bedding is still wet and vapour lifts the grout, which blooms and blisters within days. Wait at least 24 hours, 48 in winter.
- Not flushing a two-part cartridge — the first 10 cm is unmixed and never cures; purge 10-15 cm before starting.
Material and cost
Two-part epoxy grout 30-80 CNY per 400 ml cartridge, epoxy coloured sand 100-200 per set, polyurea 80-150. Supply and apply 15-40 CNY/m².
On site
- Clean cement residue and dust out of the joint first; use a rake if it is shallow, because debris prevents bonding and the whole line lifts later.
- Clean the excess within 15-30 minutes depending on temperature — once cured, scraping scratches the tile, especially matte and wood-look surfaces.
- Over underfloor heating use a flexible grout; rigid epoxy cracks and lifts under thermal movement.
Basis
- JC/T 1004-2017 Ceramic tile grouts
- GB 50209-2010 Code for acceptance of building floor construction, Chapter 6
- GB 50210-2018 Code for acceptance of building decoration, Chapter 8
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.
Cite this page
Use this format in reports, method statements or coursework. The link is permanent.
Building Calculator. Tile Grout Calculator. 2026-10-25. https://jianzhujisuan.com/en/tile-grout
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.