A procedure has been developed for characterization and optimization of gauges, based on nuclear or atomic radiation. It provides a logical and organized method to obtain the optimal design parameters of the gauge, limits of detection, resolving power, etc. The dominant concept in the procedure is a characterization function which correlates the variables that have to be measured, the design parameters of the gauge, its response and uncertainty. Gauges with linear and exponential responses were analyzed to demonstrate the generality of the approach and the use of the concepts.