Sidereal month (relative to fixed stars) is 27.32 days. Synodic month relative to Earth is 29.53. There are other months that correct sidereal for motion around

Sidereal month (relative to fixed stars) is 27.32 days. Synodic month relative to Earth is 29.53. There are other months that correct sidereal for motion around the sun, eccentricity of the lunar orbit, and tilt of lunar orbit, but the difference is tiny. https://en.wikipedia.org/wiki/Lunar_month https://en.wikipedia.org/wiki/Lunar_month