Comparison of the hydrostatic mass estimates ${\text{M}}_{500}^{\text{HSE}}$ to the true mass ${\text{M}}_{500}^{\text{True}}$ for a sample of 1655 galaxy clusters in THE THREE HUNDRED PROJECT. The blue line indicates the best-fitting linear relation, and the black line corresponds to the 1-to-1 relation. The blue line and shaded region in the lower panel show the median and 1σ dispersion of the fractional residual distribution, respectively, considering logarithmic binning. The inset shows the distribution of fractional residuals and the vertical dashed line show the median of the fractional dispersion of −0.24.