Add a Free 4-20 Ma Calculator Widget. Gain a strong understanding of the fundamentals of 4-20 mA current loops and be better equipped to decide when where or if a 4-20 mA current loop solution is right for your application. Formula To Calculate Process Variable From 4 20ma Variables Formula Process Output SqRt 4mA 4 x Output Linear 4mA The following table shows values for linear to square root extraction 4 to 20 milliamp current loop signal. . But if you want to know the exact formula for calculating 4-20 ma then please check out the Formula box above. Lets now apply this concept to a realistic 4-20 mA signal application. Microampere to Ampere Conversion Formula. There are 10E-6 ampere in a microampere ie. The Fundamentals of 4-20 mA Current Loops. The formula defines the energy E of a particle in its rest frame as the product of mass m with the speed of light. NCAT currently uses NADCON to perform three-d