MSTO width at 50% of the maximum (FWHM) as a function of cluster mass (panel a), escape velocity (panel b), and age (panels c and d). The coloured dots represent the star clusters analysed in this work. Yellow squares represent MCs clusters from Goudfrooij et al. (2014), blue squares clusters analysed by Correnti et al. (2014) and used by Goudfrooij et al. (2014) as a lower limit for the existence of the eMSTO, and YMCs analysed by Niederhofer et al. (2015) as yellow crosses. Yellow triangles show MWOCs from Cordoni et al. (2018). The yellow stars are the results by Piatti & Bastian (2016a,b). The colored dotted lines illustrate the expected MSTO width, comparing non-rotating isochrones with models for different rotation fractions - Ω/Ω_C = 0.3 (blue), 0.6 (orange), 0.8 (green), and 0.99 (red) - adopting the metallicity of [M∕H]= −0.6 (the mean of our sample). The horizontal dashed blue line represents previous limits from Correnti et al. (2014) and Goudfrooij et al. (2014), while the pink line and shaded region mark the eMSTO limit derived in this work. The black lines in panels a and b represent the linear regression for the data from Cordoni et al. (2018, dotted), Goudfrooij et al. (2014, dashed), and this work (solid). The grey shaded regions represent the standard deviation of the fit.