Turnaround radius as a function of enclosed mass. Black points: TNG-300-2 halos; yellow points: TNG-300-3 halos; magenta points: TDSS halos. The two simulations use different cosmological parameters; TDSS data points were renormalized to scale with cosmological parameters of TNG. Blue and red lines represent theoretical predictions of the spherical collapse model for maximum (asymptotic late-time) and present-time values of turnaround radius, respectively. The black line is a power-law fit (slope: 0.353 ± 0.001).