The formula for calculating true position is true position tolerance = 2 x SQRT(XVAR2 + YVAR2). In this instance, SQRT refers to a square root, XVAR refers to the amount of deviation from the basic dimension found in the X-axis, and YVAR refers to the amount of deviation from the basic dimension found in the Y-axis.
There are also web-based apps in addition to apps for iPhone, iPad and Android that can calculate true position without using the formula. Information such as position deviation on the Y-axis and X-axis will still need to be known in order to arrive at the correct conclusion.
