Grout Calculator
Enter your tile dimensions, joint width and depth, and the area to tile to find how much grout you need.
Joint depth is typically the tile's thickness.
How grout quantity is calculated
This calculator uses a standard tiling industry formula: grout (kg) = [(tile length + tile width) / (tile length × tile width)] × joint width × joint depth × 1.8 × area, where the 1.8 factor approximates grout's density in kg per liter of joint volume.
Smaller tiles need proportionally more grout than larger tiles covering the same area, since smaller tiles have more total joint length per square meter — this is why the formula's first term (combining tile length and width) scales grout usage inversely with tile size.
Frequently asked questions
Why do smaller tiles need more grout?
A given area tiled with smaller tiles has many more individual tiles, and therefore much more total joint length, than the same area tiled with larger tiles — more joint length means more grout volume needed to fill it.
What joint width should I use?
This varies by tile type and look — wall tiles commonly use 1.5-3mm joints, floor tiles often use 3-5mm, and rustic or natural stone tiles sometimes use wider joints (5-10mm or more). Check your specific tile manufacturer's recommendation.
Should I buy extra grout beyond this calculation?
Yes — it's standard practice to add 10% or so extra to account for variations in application thickness, spillage, and mixing waste, especially for a first-time or larger project.