Printed circuit heat exchangers are composed of numerous ondulated microchannels, which allow for high heat transfer performance. The particular zig-zag configuration with which the channels are designed makes it necessary to study pressure drops, since, during the design of a PCHE exchanger, an optimization between improving thermal performance and increasing pressure drops is performed. The prediction of the friction factor for the channels can be carried out using hydraulic correlations that allow to know the dependence of the pressure drops on the geometrical parameters of the channels. Although several studies have been conducted in the field of thermo-hydraulic performance of zig-zag channels, the amount of correlations in the literature is extremely limited.