The gas holdup is an important parameter for the design of slurry bubble columns. However, there is no correlation in literature to calculate the gas holdup of such reactors for industrially relevant conditions if the reactor is operated in the homogeneous regime. In this article, a novel correlation for calculating the gas holdup in the homogeneous and in the pseudo-homogeneous regimes is proposed. The correlation takes the relevant parameters into account: gas, liquid, and solid properties, sparger design, reactor diameter, and gas velocity. The correlation is also applicable for systems operated at elevated pressure and temperature. The correlation is based on 1199 data points, and it was developed by using the method of least squares. About two thirds of the data used were taken from literature (more than 20 research papers). The data from literature were carefully checked for confidence before using them for the correlation. > 90 % of the data points are covered by the new correlation with a relative error of less than 30 %, the standard deviation is 17.8 % and the averaged relative error is 9.5 %. Finally, the correlation was successfully validated with measurements which were not used to fit the correlation. ... mehrAn Excel file for using the developed correlation can be found in the Supplementary material.