Hubble’s constant (H0) is calculated using the Fundamental Plane (FP) relation between half-light radius, surface brightness, and velocity dispersion for groups and clusters of galaxies. The Tip of the Red Giant Branch (TRGB), a standard candle based on the constant luminosity of low-mass stars at helium core flash, is used to calibrate the cluster FP. TRGB stars yield the distances to the near...