GROUT CALCULATOR
The joint is part of the design. Get the quantity right first time.
This grout calculator works out how much grout a tiling job needs, in kilograms and in packs. Enter the tile length, width and thickness, the joint width and the area in m². It covers nine cement-based and epoxy grouts from Mapei and Kerakoll, works in mm, cm or m, and shows the result to the nearest 0.1 kg.
Grout figures checked: Mapei 22 October 2026, Kerakoll 23 October 2026.
FOUR MEASUREMENTS. ONE QUANTITY.
- Choose the grout. One list, nine grouts, each labelled cement or epoxy, Mapei or Kerakoll. Each grout weighs a different amount per litre, so the choice changes the answer.
- Enter the tile size and thickness. The thickness is the joint depth.
- Enter the joint width. Narrow joints read as one clean surface. Wide joints turn the grid into a pattern. If the joint is outside the width a grout is made for, the calculator flags it.
- Enter the area in m² and press Calculate. Use Copy result to drop the full line (grout, tile, joint, area, kilograms, packs) into your spec or order.
THE MATHS, IN THE OPEN
Grout fills the channel around every tile, to the full depth of the tile. Per square metre:
litres of grout = (tile length + tile width) ÷ (tile length × tile width) × joint width × joint depth
Every measurement is in mm and the joint depth is the tile thickness. Multiply by the area for the total volume, then by the grout's weight per litre for kilograms. The result is rounded to the nearest 0.1 kg, and packs are counted from that rounded figure, so the two always agree.
Worked examples (Mapei Ultracolor Plus, 3 mm joints, nothing added for wastage)
| Tile | Thickness | Grout per m² | For 10 m² |
|---|---|---|---|
| 600 x 600 mm | 10 mm | about 176 g | about 1.8 kg |
| 600 x 1200 mm | 10 mm | about 132 g | about 1.3 kg |
| 300 x 600 mm | 9 mm | about 238 g | about 2.4 kg |
| 25 x 25 mm mosaic (2 mm joint) | 4 mm | about 1.13 kg | about 11.3 kg |
Bigger tiles, fewer joints, less grout. Mosaics flip it: joints everywhere, so far more grout per m².
The sizes in this table illustrate the maths. They aren't Archi.tile products.
ONE FLOOR, THREE GROUTS
600 x 600 mm tiles, 10 mm thick, 3 mm joints, 10 m²:
| Grout | Type | Result | Packs | With 10% wastage |
|---|---|---|---|---|
| Mapei Ultracolor Plus | Cement-based | about 1.8 kg | 1 x 2 kg bag | about 2 kg (1.8 + 0.2) |
| Kerakoll Fugabella Color | Cement-based | about 1.3 kg | 1 x 3 kg bag | about 1.5 kg (1.3 + 0.2) |
| Kerakoll Fugalite Color | Epoxy | about 1.6 kg | 2 x 1.5 kg tubs, or 1 x 3 kg tub | — |
Same joint, different grout, different weight. That's why the grout comes first.
WASTE IS A CHOICE. MAKE IT ON PURPOSE.
The first answer is the grout that fills the joints, nothing more. That's the number to compare across products.
For the order, tick Add extra for wastage and choose 5%, 10% or 15%. The extra goes on the unrounded weight and the total is rounded up to the next 0.1 kg. The answer shows the split, for example "1.8 kg + 0.2 kg extra for wastage (10%)", so the allowance is visible in your spec, not buried in it.
Rough or textured tiles and uneven substrates can take more. Specify one batch for the whole job.
MAPEI OR KERAKOLL
All nine grouts sit in one list, labelled by type and brand.
Mapei: Keracolor FF, Keracolor GG, Keracolor SF, Ultracolor Plus, Kerapoxy, Kerapoxy CQ, Kerapoxy Easy Design.
Kerakoll: Fugabella Color (cement-based), Fugalite Color (epoxy).
Joint widths we can confirm from the data sheets: Ultracolor Plus 2–20 mm, Keracolor FF up to 6 mm, Keracolor GG 4–15 mm, Fugabella Color up to 20 mm, Fugalite Color up to 10 mm. For the others, check the grout's data sheet.
Why Kerakoll's own calculator gives more. Two different questions. Kerakoll's figures include an allowance for waste on site. Ours gives the grout that ends up in the joints, then lets you add 5, 10 or 15% with the wastage box. So with the box unticked, our Kerakoll figure is lower. Tick it if you want a buffer built in.
Mapei figures give the same answers as Mapei UK's own online grout calculator.
Pack sizes can vary by colour: check your colour comes in the size you need.
GROUT, ANSWERED
How much grout per m² for 600x600 tiles?
About 176 g per m² for 600 x 600 mm tiles, 10 mm thick, with 3 mm joints, using Mapei Ultracolor Plus. Over 10 m² that's about 1.8 kg, or one 2 kg bag. A thicker tile, a wider joint or a heavier grout pushes the figure up, so enter your own spec in the calculator above.
How do you calculate grout quantity for tiles?
Litres per m² equals (tile length + tile width) divided by (tile length × tile width), multiplied by the joint width and the tile thickness, all in millimetres. Multiply by the area for the total, then by the grout's weight per litre for kilograms. The calculator does this for you and rounds to the nearest 0.1 kg.
Do large format tiles use less grout?
Yes. A large tile has fewer joints in each square metre, so it takes less grout. At the same thickness and joint width, a 600 x 1200 mm tile needs about a quarter less grout than a 600 x 600 mm tile. The joint depth still matters: a thicker large format tile holds more grout per metre of joint.
What size do I enter for a mosaic?
Enter the size of one small tile, not the sheet. The grout runs between the small tiles, so the sheet size gives far too little. Mosaics have a dense grid of joints, which is why they need much more grout per m² than large formats. Measure one tile, every time.
Is wastage included in the grout figure?
Not unless you ask for it. The first answer is only the grout that fills the joints. Tick Add extra for wastage and choose 5, 10 or 15%: the extra goes on the unrounded weight, the total is rounded up to the next 0.1 kg, and the result shows the split, so the allowance is visible in your spec.
Which joint widths does each grout cover?
From the data sheets we hold: Mapei Ultracolor Plus 2 to 20 mm, Keracolor FF up to 6 mm, Keracolor GG 4 to 15 mm, Kerakoll Fugabella Color up to 20 mm and Fugalite Color up to 10 mm. If your joint is outside a grout's range, the calculator still answers and adds a note. For other grouts, check the data sheet.
Why is the Kerakoll quantity lower than Kerakoll's own figure?
Because Kerakoll's own figures include an allowance for waste on site, and ours don't until you add it. Our calculator works out the grout that ends up in the joints. To build in a margin, tick the wastage box and choose 5, 10 or 15%. That way the allowance is your decision and is shown separately.
Does the grout calculator work for epoxy grout?
Yes. It includes four epoxy grouts: Mapei Kerapoxy, Kerapoxy CQ and Kerapoxy Easy Design, and Kerakoll Fugalite Color. Epoxy weighs a different amount per litre from cement-based grout and comes in tubs or kits rather than bags, so the calculator uses each grout's own weight and pack sizes.
How are the packs counted?
From the kilograms shown, so the two always agree. The calculator lists the count for every pack size the grout comes in. For 1.8 kg of Ultracolor Plus that's one 2 kg bag, or one 5 kg or 22 kg bag. Pack sizes can vary by colour, so confirm your colour comes in the size you plan to order.
Can I put the result into a specification?
Yes. Press Copy result and the calculator copies one line with the grout name, tile size, thickness, joint width, area, the kilograms and the packs. Paste it into your spec, schedule or order. If you've ticked the wastage box, the line says how much extra is included, so nobody adds it twice.
Still got a question? Talk to our team.
