The phenomenon of relaxation (reduction of assembly preload) of bolted connections has been known for a long time. At present, it is possible to take this phenomenon into account already in the design and strength calculation of prestressed bolted connections. The amount of relaxation (plastic permanent deformation, settlement) of a bolted connection in micrometers is usually estimated based on recommendations. These recommendations for estimating the amount of relaxation of a bolted connection are based on performed experiments and practical experiences. This paper describes one of the way to verify the magnitude of relaxation of a bolted connection by a simple experiment.