Grout Calculator
This grout calculator finds how much grout you need from the tile size, the joint width and depth, and the area. Enter them and the grout calculator returns the grout in kilograms and per square metre. As a tile grout calculator it turns a grout estimate into a bag count so you buy the right amount.
Results
The Grout Calculator is part of our Floor & Wall collection. Browse more floor & wall to size, convert, and check your work alongside this tool.
What the grout calculator shows
Grout fills the joints between tiles, and the grout calculator works out how much that takes. It finds the share of the surface that is joint from the tile size and joint width, multiplies by the joint depth for a volume, and turns that into a weight. Whether you run it as a tile grout calculator, a grout coverage calculator, or a grout quantity calculator, it answers how much grout you need.
How the grout calculator finds the amount
The grout calculator uses the joint fraction, the depth, and the grout density:
L and W are the tile sizes, and the density of grout is about 1.6 kg per litre. Smaller tiles have more joint per square metre, so a mosaic uses far more grout than a large format tile. This grout calculation formula is why the tile size matters as much as the joint width.
Grout coverage calculator example
A 10 m² floor with 300 by 300 mm tiles, 8 mm thick, and 3 mm joints. The grout coverage calculator gives:
So the floor needs about 2.56 kg of grout. Change the tile size or joint and the grout calculator updates the amount at once.
How to use the grout calculator
Enter the tiled area in square metres, the tile length and width in millimeters, the tile thickness, and the joint width, then the grout calculator returns the grout in kilograms and per square metre. Smaller tiles and wider joints both use more grout. For a grout estimate across rooms, add the areas first, or run each area and total the results.
Reading the grout calculator result
The kilogram figure is what you buy; divide it by the bag size for the number of bags, and round up. Coverage per kilogram falls as tiles get smaller or joints get wider, so a mosaic or a wide rustic joint needs several times the grout of a large tile with a fine joint. Epoxy grout is denser than cement grout, so an epoxy grout calculator gives a slightly higher weight for the same joints. Keep a little spare, since mixing and cleanup waste some.
When to use the tile grout calculator
- Buying grout for a floor or wall with the tile grout calculator
- Getting a grout estimate before a supply run
- Checking coverage with a grout coverage calculator
- Comparing cement and epoxy grout amounts
Common grout calculator mistakes
- Ignoring tile size. Small tiles have far more joint per m², so a grout estimate must use the real tile size.
- Wrong joint depth. Use the tile thickness for the joint depth, or the grout volume calculator reads low.
- Forgetting waste. Mixing and cleanup waste some, so calculate grout needed with a little spare.
Tips for grouting
- Measure the real tile and joint, since both drive the amount.
- Divide the kilograms by the bag size and round up.
- Keep one spare bag on a large floor.
Grout estimate by tile size and joint
A good grout estimate starts with the tile, not the room. Grout fills the joints, so the amount depends on how much joint there is per square metre, which is set by the tile size and the joint width. Halve the tile size and you roughly double the joint length per square metre, which is why a mosaic can use five or six times the grout of a large format tile over the same floor. The joint depth, usually the tile thickness, and the joint width then scale the volume. To calculate grout needed accurately, measure the real tile and joint rather than assuming, and remember that a tile and grout calculator only gives the grout; the adhesive under the tiles is a separate estimate handled by the mortar calculator.
Epoxy grout calculator and coverage per bag
Bag counts come from the weight, so an epoxy grout calculator and the grout coverage per bag figure work together. Divide the total kilograms by the bag size, commonly 2, 5, 10, or 25 kg, and round up. Epoxy grout is denser and often sold in smaller units, so the same joints give a slightly higher weight and more, smaller bags. Cement grout is lighter and cheaper for large plain areas. Whichever you use, the tile grout coverage per kg drops as joints widen, so a rustic wide joint or a mosaic needs noticeably more bags. Buy one spare bag on a big job, since offcuts and cleanup always waste a little.
Tile grout coverage per square meter
Approximate grout per square metre by tile size at a 3 mm joint and 8 mm depth, for the tile grout coverage per square meter figure:
| Tile size | Joint fraction | Grout per m² |
|---|---|---|
| 100 × 100 mm (mosaic) | 0.060 | 0.77 kg |
| 200 × 200 mm | 0.030 | 0.38 kg |
| 300 × 300 mm | 0.020 | 0.26 kg |
| 600 × 600 mm | 0.010 | 0.13 kg |
Grout Calculator FAQ
How does the grout calculator work?
It finds the joint fraction from the tile size and joint width, multiplies by the joint depth and the grout density, and scales by the area. The grout calculator returns kilograms and per square metre.
How much grout do I need per square metre?
It depends on the tile. A 300 mm tile at a 3 mm joint needs about 0.26 kg per m², while a 100 mm mosaic needs about 0.77 kg per m². Smaller tiles use more grout.
Does epoxy grout use more?
Slightly. Epoxy grout is denser than cement grout, so an epoxy grout calculator gives a higher weight for the same joints.
What is the grout calculation formula?
Grout per m² equals ((L + W) times joint width divided by L times W) times joint depth times density. The grout calculator applies it for you.