Use this grout calculator to estimate how much grout you need for a tiling job. Enter the tiled area, the tile size and thickness, the joint width, and a waste allowance. The tool outputs grout only.
How This Calculator Works
Coverage is calculated from the tile dimensions, tile thickness, and joint width. That coverage rate is then multiplied by the tiled area, and the waste percentage is added. The total is rounded up to whole pounds, because grout is bought in whole amounts.
Worked Example
For 12 x 12 inch tiles that are 0.25 inches thick, with a 0.125 inch joint, over 100 square feet: coverage is 0.08 pounds per square foot, which is 8 pounds before waste, and 9 pounds with a 10% waste allowance. As a secondary line only, that is 1 bag of 25 pounds.
Example Results
| Area | Tile | Joint | Grout with 10% waste |
|---|---|---|---|
| 100 sq ft | 12 x 12 in | 0.125 in | 9 lb |
| 200 sq ft | 12 x 12 in | 0.125 in | 18 lb |
| 100 sq ft | 6 x 6 in | 0.125 in | 19 lb |
| 100 sq ft | 12 x 12 in | 0.25 in | 19 lb |
Frequently Asked Questions
How much grout do I need for 100 square feet?
It depends on tile size, thickness, and joint width. With the default example above, the answer is 9 pounds including 10% waste.
Does a wider joint use more grout?
Yes. A wider joint leaves more space to fill, so coverage per square foot rises and the total pounds rise with it.
Do larger tiles use less grout?
Usually, yes, because larger tiles have fewer joints per square foot. Enter your exact tile size to check your own job.
Why add waste?
Waste covers spillage, mixing loss, and cuts around edges and fixtures. The default is 10%, and you can change it.
Does this calculator count tiles or thinset?
No. This tool outputs grout only. It does not calculate tile count or thinset.
Should I check the grout manufacturer’s coverage?
Yes. Use this estimate for planning, then check the product you buy, because coverage varies by product and application.
Method and Notes
Coverage (pounds per square foot) = ((tile length + tile width) x tile thickness x joint width x 16) / (tile length x tile width). Coverage is rounded to two decimal places before it is multiplied by area, so the worked example reproduces exactly: 0.08 x 100 = 8 pounds before waste, and 8 x 1.10 = 8.8, rounded up to 9 pounds. The 25 pound bag line is secondary only and is the total rounded up to whole 25 pound bags.
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Disclaimer
This calculator is for planning only. It is not professional tiling advice, and it does not replace the manufacturer’s instructions or a qualified installer. Verify coverage, joint width, and product requirements before you buy.