Convert Month (month) to Month (Synodic) (month (synodic)) instantly.
About these units
Month (month)
A month traditionally reflects the lunar cycle, which lasts about 29.53 days (a synodic month). Ancient cultures used lunar months to track seasons, religious festivals, and agricultural cycles. In modern civil calendars, however, months are fixed lengths of 28–31 days to maintain alignment with the solar year. This creates a hybrid system: culturally grounded in the Moon, yet functionally tied to Earth's orbit around the Sun. Months remain one of the most intuitive time units for planning—budget cycles, billing periods, academic schedules, subscription systems, and medical dosing regimens all rely heavily on monthly intervals.
Month (Synodic) (month (synodic))
A synodic month is the time the Moon takes to complete a full cycle of phases—from new moon to new moon—lasting about 29.53059 days. Unlike the simple geometric orbit of the Moon, the synodic period aligns with the Sun–Earth–Moon relationship, making it tied to how humans perceive the Moon's illumination cycle. This is the month that shaped nearly all ancient calendars, from Babylonian to Hebrew, Islamic, and Chinese systems. Religious festivals, agricultural cycles, and early navigation practices all relied on the regularity of the synodic month. Even today, while civil calendars use fixed months, astronomical calculations and lunar calendars still depend on synodic months to track tides, eclipse cycles, and the dynamics of Earth's only natural satellite. The synodic month illustrates how natural celestial rhythms guided early human civilization.