Grout Calculator
Grout quantity depends on four things: tile size, tile thickness, joint width and the density of the grout. Enter those measurements to estimate kilograms or pounds and whole bags. Use the coverage examples below to compare tile sizes, then check the selected grout manufacturer’s consumption data.
Your measurements
Check your order
Your tiling order
- Confirm tile size, laying pattern, joint width, allowance and tiles per box.
- Use the adhesive maker’s coverage for the required trowel, tile and substrate.
- Estimate grout separately and check that the grout and float suit the tile finish.
Tools for this job
Once the joint volume is estimated, a suitable float helps press grout into the joints without damaging the tile finish.
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- Work grout into tile joints
Grout float
QEP 10060 rubber grout float
For working grout into the joints after tiles are installed. Choose a float suitable for your grout and tile finish, and follow the grout maker's instructions.
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How much area does a 5 kg bag of grout cover?
There is no single coverage figure for a 5 kg bag. Smaller tiles create more joints per square metre, so the same bag covers less area. These examples use a 10 mm joint depth, 3 mm joint width and a consumption factor of 1.6 kg/L; they exclude waste and whole-bag rounding.
| Tile size (mm) | Grout (kg/m²) | Area per 5 kg bag (m²) |
|---|---|---|
| 100 × 100 | 0.96 | 5.2 |
| 300 × 300 | 0.32 | 15.6 |
| 600 × 600 | 0.16 | 31.3 |
| 600 × 1200 | 0.12 | 41.7 |
For 600 × 600 mm tiles, the theoretical coverage is 5 ÷ 0.16 = 31.25 m². With a 10% allowance it becomes 5 ÷ (0.16 × 1.10) = about 28.4 m². For your order, multiply the unrounded rate by the area and allowance, divide by the bag weight, then round up.
The factor comes from the product, not just its broad grout type. MAPEI’s Ultracolor Plus consumption guidance is one example; use your chosen product’s current data for the actual order. These are calculated examples, not guaranteed product coverage.
The grout formula
Where A and B are the tile length and width in millimetres, C is the tile thickness in mm, D is the joint width in mm and Density is the grout density in kg per litre (about 1.6 for standard cement grout).
The bracketed part gives the joint length per square metre; multiplying by thickness and joint width gives the joint volume in litres per m²; multiplying by density converts it to kilograms. This is the same formula tile manufacturers print on their technical data sheets.
Worked example
600 x 600 mm porcelain, 10 mm thick, 3 mm joints, standard cement grout on a 12 m² floor.
(600 + 600) ÷ (600 × 600) = 0.003333. × 10 mm × 3 mm = 0.10 litres per m². × 1.6 kg/L = 0.16 kg/m². Over 12 m² that is 1.92 kg, plus a 10% allowance = 2.1 kg, so a single 5 kg bag covers it with plenty spare.
Grout usage by tile size
Small tiles use dramatically more grout than large ones, because there is far more joint length per square metre. A mosaic sheet can use six times the grout of a large-format porcelain tile.
| Tile size (mm) | 2 mm joint | 3 mm joint | 5 mm joint |
|---|---|---|---|
| 100 x 100 | 0.64 | 0.96 | 1.60 |
| 150 x 150 | 0.43 | 0.64 | 1.07 |
| 200 x 200 | 0.32 | 0.48 | 0.80 |
| 300 x 300 | 0.21 | 0.32 | 0.53 |
| 300 x 600 | 0.16 | 0.24 | 0.40 |
| 600 x 600 | 0.11 | 0.16 | 0.27 |
| 1200 x 600 | 0.08 | 0.12 | 0.20 |
Sanded or unsanded?
- Unsanded for joints up to about 3 mm, and for any polished, glazed or soft-glaze tile that sand would scratch. Typical density 1.5 kg/L.
- Sanded for joints of 3 mm and wider, and for floors, where the sand reduces shrinkage and adds compressive strength. Typical density 1.8 kg/L.
- Epoxy for wet rooms, commercial kitchens and anywhere that needs chemical or stain resistance. It is far more expensive and has a short pot life, so mix small batches.
Why you should add 10%
The formula assumes the joints are exactly as deep as the tile is thick and perfectly filled. In practice adhesive squeezes into the bottom of some joints (using less grout) while uneven tile backs and slightly wider cut joints use more. The 10% allowance also covers what stays in the bucket, on the float and in the sponge water.
If you are grouting for the first time, use 20%. Running out halfway through a wall means a visible colour break, because the second batch never dries to exactly the same shade.
Sources and assumptions
The model estimates joint volume from tile length, width, depth and joint width, then multiplies by the selected consumption factor. The familiar (A + B) / (A × B) approximation uses all tile and joint dimensions in millimetres.
- MAPEI Ultracolor Plus: consumption formula and application sheet: The sheet gives (A + B) / (A × B) × C × D × 1.6 kg/m² for Ultracolor Plus. That 1.6 factor is product-specific.
Before using this estimate
- The other consumption factors are estimates, including the epoxy option. Compare with the exact grout product calculator or coverage table before buying.
- Tile bevels, adhesive in the joints and cleanup losses change consumption. Follow the grout instructions for mixing; epoxy kits do not use the cement-grout water ratio.
Source notes reviewed . See how we check calculations and handle corrections.
Planning your order
Check the inputs before buying: measure the surfaces you need, then apply an allowance and round to whole packs. The guides include worked examples you can follow alongside this calculator.
Published by OrderEnough. This is a planning estimate: check the product specification and the assumptions above before ordering. Last updated . Read how we source our figures on the methodology page.