Precision luminosity evaluation is an essential ingredient to cross section measurements at the LHC, needed to determine fundamental parameters of the standard model and to constrain or discover beyond-the-standard-model phenomena. The latest luminosity-related results of the CMS experiment are reported. The absolute luminosity scale is obtained with transverse beam-separation “van der Meer” scans, and the systematic biases are studied in detail using innovative methods. Contributions to the uncertainty in the integrated luminosity due to instrumental effects, including the linearity and stability of the detectors, are also discussed. Constraining the luminosity integration uncertainty via the observed rate of Z$\rightarrow\mu^+\mu^-$ events is explored.