Caliper is the thickness of a paper or board. Caliper is expressed as points in the English system, with one point of caliper representing .001 inch in thickness. In the metric system, caliper is expressed in microns. Unless otherwise stated, TAPPI Test Method T411 is the standard procedure used for measuring caliper. The caliper of combined board is also measured using TAPPI Test Method T411 to measure the thickness of the combined product.