Author Michael Krystek explains the principles of calculating measurement uncertainty in an easy-to-understand, step-by-step manner. Practical examples for different types of measurement are also given.This work is based on the internationally renowned ISO/IEC Guide to the Expression of Uncertainty in Measurement (GUM). The "GUM" defines standard methods of calculating and expressing the uncertainty of measurement to help make results more comparable. This is especially important for calibration. In Germany, the GUM is used as the basis for expressing uncertainty on official calibration certificates, such as those issued by the German Calibration Service (DKD).