Tile spacers come in a variety of sizes ranging from 1/32 of an inch to 1/4th of an inch wide. The size of the spacers used determines the ultimate width of the grout lines.
Generally, smaller tile spacers are used for wall tiles, while larger spacers are used for floor tiles. Any tile job using spacers smaller than 1/8th of an inch should be done with unsanded grout; sanded grout should be used only for larger joint sizes. The tiles, tile bevel, spacing preference and where the tile is installed all are factors that affect the needed size of spacers.