Caliber range is defined in ANSI A137.1 Specification for Ceramic Tile as, “an acceptable size range for tiles to be used in the same installation.” In other words, this is what determines how much size variation can exist between tiles on the same job. This is important as it relates to whether or not the layout of an installation looks good with even joints throughout.

ANSI A137.1 has specific caliber range requirements for mosaic tile, quarry tile, pressed floor tile, glazed wall tile, and porcelain tile. The range is dependent on whether the tiles have natural, calibrated, or rectified edges (click here to learn more about this). To confirm that a product meets the caliber range requirements, a sample of the lot is tested according to the ASTM C499 test method for facial dimensions.

The requirements in A137.1 limit how much each side of every tile tested can vary from the overall average of the tiles tested. For example, the standard states that for pressed floor tiles with rectified edges each side of each tile tested shall not vary more than plus or minus 0.25% (or 0.03 inch, whichever is less) from the overall average. If the overall average size of all the samples tested is 8″, then each side of every tile tested should not be less than 7.98″ or more than 8.02″ (0.25% of 8″ = 0.02″). That’s a full range of only 0.04″ (or 1/25″).

For larger tiles, like rectified pressed floor tiles with an average size of 24″, each side of each tile can vary no more than plus or minus 0.03″ (slightly less than 1/32″) from the average, as opposed to calculating plus or minus 0.25%.

The full ANSI A137.1 specification can be purchased via the link below.

ANSI A137.1 Specification for Ceramic Tile

Also, for information about TCNA’s testing services click here.

Check back, next time we will discuss “What is Nominal Size?”