Basic Information: The traditional/historical size of the tiles is 13 x 13cm, which is about 5-3/8" square. I use a measurement of 5-1/2" square when drawing out a design – this allows for a minimal grout line. Here are some other basic guidelines.
Horizontal Calculations: Determine the center-point on the wall to be your focal point, and measure to the right and left of that point. With that measurement decide if the center-point will be a tile or a grout line. Be sure it is visually balanced.
Vertical Calculations: If your backsplash is a standard 18" high, you will need about 3-1/2 tiles from the countertop to the bottom of cabinets. You may want to put the cut edge at the top or work from the cabinet down, with the cut edge along the countertop.
Decorative Tiles: We generally use about 25-30% of the tiles as decorative inserts (picture tiles) especially if you are doing a large area. The balance should be Blanks with decorative corners that meet together. Suggestion: do not put decorative tiles in the corners, where their beauty will be lost.
Horizontal Calculations: Follow directions as above for determining the center point.
Vertical Calculations: Measure the heights of the sides and consider how many tiles will fit. Decide if you want to use decorative tiles and where they will be set.
It may help to draw this out on graph paper. Usually the fireplace surround will use many more decorative tiles than a backsplash area. Some Building Codes require 8" between the firebox and the outside walls. By using a decorative border piece with a basic tile you can easily address this requirement.A Checklist/Questions to Ask Before Placing an Order