Determine the tolerance of the tool. Consult the manufacturer's technical literature to find the tool's accuracy. For example, a manufacturer may specify that the alignment of a saw is accurate to within 1/10-inch.
Locate the tolerance of the calibration standard. Refer to the technical literature for the tool or standard if you do not have the tolerance readily available. For example, a laser distance meter might have an accuracy of 6/100-inch.
Reduce the ratio of calibration standard to tool accuracy. Divide the accuracy of the tool being calibrated by the accuracy of the calibration standard. For example, .1 divided by .006 equals 16.667. Express the result as the test accuracy ratio, such as 16.667:1.