1/8-Inch Trowel

• The smallest tiles on the market are known as mosaic tiles, and they can come in ceramic and porcelain versions that are thinner than the natural-stone types. Natural-stone mosaics can range in thickness from a 1/4 inch up to 1/2 inch, and the 5/8-inch tiles still utilize the same trowel as the others, which is a 1/8-inch notched trowel.
  
  

1/4-Inch Trowel

• A 1/4-inch trowel can be used for any tile up to 12 inches on the face dimensions, regardless if they are 3/8-inch thick or 5/8-inch thick. The key with any tile installation is to apply enough thinset or adhesive to bond the tile, but not so much that it oozes up between the joints. A 1/4-inch trowel is sufficient for the most common sizes of tiles.
  
  

3/8-Inch Trowel

• While the industry standard for years was a 1/4-inch notch for tiles up to 12 inches, many professionals prefer to use a 3/8-inch trowel for 12-inch pieces. Otherwise the 3/8-inch notched trowel is generally reserved for anything from 12- up to 16-inch pieces. This applies to all thicknesses of tile, although if you are working with natural stone material that varies in thickness, you may need to apply extra mud to the thinner sections of the tiles.
  
  

1/2-Inch Trowel

• The largest types of natural stone and ceramic tiles require a 1/2-inch notched trowel to provide sufficient coverage. Regardless if you are working with 1/4-inch material or 5/8-inch material, you need to provide sufficient adhesive for the large-bodied tiles, and anything smaller than a 1/2-inch trowel will result in tiles falling off the wall or popping off the floor.