Numerical results for the ratio between the radius of gyration and the hydrodynamic radius, 𝑅 ℎ , of self-avoiding walks are close to 1.58. A numerical test in the dilute regime using our simulation model for star polymers with a number of Kuhn segments comparable to the experiments provides 1.57. Experimental data lead to a ratio 𝑅 𝑔 /𝑅 ℎ that is typically smaller by 10-20 % as compared to these numerical data, mainly due to the assumptions made for computing 𝑅 ℎ . Therefore, we use 𝑅 𝑔 /𝑅 ℎ ≈ 1.35 ± 0.08 to estimate 𝑅 ℎ . These results are combined with the viscosity data to compute the ratio