The significant difference of the Hubble constant value estimated from the local distance ladder and from the cosmic microwave background radiation attracts substantial attention in the recent decade and has been dubbed as Hubble tension. Many researchers set out to find the source of Hubble tension, e.g. identifying the possible errors in distance estimation and exploring new theories or physical causes to fix the possible problems in the ΛCDM model. However, the tension is still unresolved. This paper examines the process of converting redshift to recessional velocity and reveals that the converting formula for local estimations is inappropriately approximated. By using the relativistic Doppler effect formula, the paper reduces the estimated Hubble constant from Cepheid method by 6%, agreeing with the estimates from the CMB method at about 1σ level. It is expected that the right formula can bring the estimates from the TRGB method to the same level of the CMB estimates, so the Hubble tension should disappear.