How to use
- Enter the area that will actually be tiled.
- Enter one tile's width and height in inches.
- Enter the joint width and the depth you will fill. Depth is often a bit less than the tile thickness.
- Press Calculate. Divide the cubic feet by the yield on the bag to get a bag count.
How it's calculated
Each tile sits in a module of (width + joint) by (height + joint). The joint area for that module is the module minus the tile face. Corners are included once.
Tile count = area in square inches ÷ module area. Joint volume in cubic inches = that count × joint area × depth. Cubic feet = cubic inches ÷ 1,728.
Worked example
Fifty square feet of 12 by 12 tile with a 1/8 inch joint and a 1/4 inch depth is about 49 tile modules and about 0.021 cubic feet of joint. That is a small volume because the joint is thin. A sanded grout bag might cover several times that. Read the bag. The tile calculator on this site counts tiles. It does not compute this volume.
Assumptions
A regular grid and one tile size. Brick-laid offsets change the joint path slightly. The volume is the gap, not a recommendation of a product.
FAQ
Why is the volume so small?
A 1/8 inch joint, a fraction of an inch deep, is a thin ribbon. Large format tile makes it smaller still.
How do I get bags?
Divide cubic feet by the cubic feet one bag yields at your joint size, if the bag states it that way. Some bags state square feet of tile at a joint size. Use that coverage instead of this volume if it matches your tile.
Does unsanded grout change the math?
The volume of the joint does not change. The yield per bag might.
Should joint width be zero?
Zero width means the tiles touch and there is no joint volume to fill. The page rejects a joint that does not add area.