Tile Estimator

Mosaic Tile Calculator

How much tile do you need? You’ll know in just 4 quick steps . . .

1. Measure Your Surface

Measure the dimensions of the surface you would like to mosaic and calculate the area using the formulas from elementary school:

  • RECTANGLE AREA = length x width
  • TRIANGLE AREA = 1/2 x width x height
  • CIRCLE AREA = 0.785 x diameter x diameter
Triangle Diagram
To get the area of a triangle you multiply the height by the width, and then divide by two.
Circle Diagram
To get the area of a circle you square the diameter and then multiply the result by 0.785

Keep in mind that 1 ft2 is 144 in2.

If you get your answer in square inches, just divide by 144 to get the answer in square feet.

We have help with the formulas at the bottom of the page if you need it.

2.  Look Up An Estimate

Now look up an estimate of the number of mosaic tiles you need based on square footage. Except for 8mm and 3/8 inch tile, these estimates assume a grout spacing of 1/16 inch between the tiles. The 8mm and 3/8 inch numbers are based on a smaller grout gap of 1/32 inch. The first three columns refer to mosaic marble stone of different types. The fourth column refers to 3/4-inch glass mosaic tile. Remember that 1 ft2 is 144 in2.

# of Square Feet3/8";9/16";3/4";8mm12mm

3. Are you cutting the tiles?

Cutting a mosaic tile in pieces theoretically decreases the amount of tile you need. How is this so? You will have more pieces, so there will be more grout lines in the mosaic. More grout lines means more grout and less mosaic tile. The effect can be significant. For example, it requires 218 of the 3/4″ glass mosaic tiles to cover 1 square foot with a grout spacing of about 1/16 inch, but if you cut the tiles into pieces, you might only need 200 tiles. On the other hand, people who cut tile probably should budget a little extra as waste. That’s why we use 218 per square foot as a rule of thumb for 3/4″ mosaic tile.

4. Consider the Spacing Between Tiles

Tile coverage is determined as much by the grout spacing between the tiles as it is by the area you are covering. All of the calculations in our tables assume a standard grout spacing for that particular size. Grout gaps of standard size ensure that grout penetrates between the tiles and covers the adhesive underneath, while the hairline crack between “touching” tiles can never be grouted reliably. Standard size grout gaps are also optimal for aesthetic reasons, while using no grout gap between tiles of similar color does not look like distinct pieces at a distance. For advice about choosing a grout color, see our page of Mosaic Instructions.

Note that 3/4″ glass mosaic tile sometimes comes face-mounted on paper so that the installer can glue the whole sheet to a wall and then peel the paper off the face of the tile and then grout. These sheets are made according to metric standards, so that the grout spacing is slightly larger than 1/16″. Typically there are 225 tiles mounted on a sheet that is 1.15 square feet. Our metallic glass mosaic tiles and swirled glass mosaic tiles are cut from such sheets. Most artists remove the tiles from the sheets before using, so this doesn’t matter.

Help with the Formulas

Rectangle Area
length x width
length (in)width (in)area (feet²)
Triangle Area
half width x height
width (in)height (in)area (feet²)
Circle Area
0.785 x diameter²
diameter (in)area (feet²)