Grout Calculator
Estimate the grout needed to tile an area.
Results update as you type.
How it works
Grouting fills the joints between tiles, and this calculator estimates how much grout you need so you buy the right number of bags without running short mid-job or wasting money on excess. You enter the tile length and width, the tile thickness, the width of the grout joint, and the total area you are tiling, and it returns the grout needed in kilograms and pounds plus the coverage per square meter. The amount of grout depends on how much joint volume there is to fill: smaller tiles have more joints per area and need more grout, thicker tiles have deeper joints, and wider grout lines obviously use more. The formula multiplies tile perimeter contribution by thickness, joint width, and grout density, then divides by the tile face area to give a per-square-meter figure. Because mixing, waste, and uneven substrates always consume a little extra, it is wise to buy about ten percent more than the calculated amount, and to round up to whole bags. This estimate works for wall and floor tiles, ceramic and porcelain, and both sanded and unsanded grout. Enter your tile dimensions, joint width, and area to see how much grout to buy.
Grout (kg/m²) = ((L + W) × T × J × 1.8) / (L × W)
This standard tiling estimate multiplies the sum of the tile length and width by the tile thickness, the joint width, and grout density (about 1.8), then divides by the tile face area. That gives grout per square meter, which multiplied by your total area yields the total grout weight needed.
Source:Tile industry grout coverage estimate
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter tile length, tile width, tile thickness, joint (grout line) width and area to tile.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Grout needed updates instantly as you type — no button to press.
Frequently asked questions
How much grout do I need per square meter?
It depends on tile size, thickness, and joint width. Smaller tiles and wider joints need more grout because there are more or larger gaps to fill per area. For typical 300 mm tiles with 3 mm joints and 8 mm thickness, expect roughly 0.3 kilograms per square meter. The calculator gives a precise figure for your exact tiles.
Why do smaller tiles use more grout?
Smaller tiles create more joint length within the same floor or wall area, since there are many more tiles and therefore many more grout lines to fill. Mosaic and small-format tiles can use several times the grout of large-format tiles for the same area. That is why the tile dimensions strongly affect the total grout you should buy.
Should I buy extra grout?
Yes. It is smart to buy about ten percent more grout than the calculated amount to cover mixing waste, spillage, uneven tile backs, and slightly wider joints in places. Running out partway through can leave you with a color-matching problem if a new batch differs slightly, so a small surplus is cheap insurance for a consistent finish.
What is the difference between sanded and unsanded grout?
Sanded grout contains fine sand and is used for wider joints, typically 3 millimeters and above, because the sand resists shrinkage and cracking in larger gaps. Unsanded grout is smoother and used for narrow joints under 3 millimeters and for delicate surfaces that sand could scratch. Both are estimated with the same volume-based approach this calculator uses.
Does tile thickness really matter?
Yes, because the grout joint is as deep as the tile is thick, so thicker tiles create deeper joints that hold more grout. A floor tile 10 millimeters thick uses noticeably more grout than a 6-millimeter wall tile of the same face size and joint width. That is why the calculator asks for tile thickness along with the joint width.