Use the grout manufacturer's coverage per bag
When your product supplies a coverage value for the exact tile size, joint width and fill depth, enter it in Manufacturer coverage per bag. The calculator will use your published coverage rather than an assumed dry-material density. If you leave it blank, the tool uses a geometric approximation that may differ substantially from a particular formula or grout chemistry.
As an example of product-specific guidance, see the MAPEI Flexcolor CQ published coverage chart (PDF). Coverage always depends on the grout product and job conditions.
How to use this grout calculator
- Enter your project dimensions and choose US or metric units.
- Check the product coverage or yield on its packaging. Optional prices are in USD.
- Select Calculate to see your estimate. If you change measurements, calculate again.
- Save the valid result to your project board, copy its link or print it.
The calculation explained
The model calculates what fraction of a repeating tile grid consists of joints. It multiplies that fraction by the total tiled area and the selected filled joint depth, then estimates weight using a user-selected approximate grout density.
Worked example
For a 12 × 12 in tile with a 1/8 in joint, the joint area is a small fraction of the surface. The required material also depends on how deep the joint is filled and the material’s yield, so check the product label.
What to check before you buy
Because actual grout coverage depends on tile edge geometry, installation depth, product composition and packaging, this estimate is a cross-check rather than a substitute for manufacturer coverage tables.
These figures are estimates, not final purchase orders, professional installation instructions or engineering advice. The product packaging and site conditions take precedence over default values. When in doubt, confirm with a qualified contractor, supplier or relevant professional.
Frequently asked questions
Is this a manufacturer coverage calculator?
No. It is a geometric estimate with an editable assumed density. Compare the result against your specific grout brand’s coverage chart.
Why does narrower tile require more grout?
More joints usually occur per square foot when tiles are smaller, increasing joint volume.
What is the default grout density?
The default is only a planning assumption of 100 lb/ft³. Use a product-specific value if the manufacturer provides it.
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Metric worked example
If 12 m² needs grout, one 5 kg bag covers 5 m² for your exact tile and joint, and you add 10%, the estimate is 13.2 kg and 3 bags.