Convert Sidereal Months to Months
Convert Sidereal Months (sid.mo) to Months (mo) instantly and accurately.
Conversion Formula
mo = sid.mo × 0.8976500278
About Sidereal Months
The sidereal month = Moon's orbital period relative to the fixed stars = 27.3217 days = 2,360,591.6 s - the shortest lunar month. It is ~2.21 days shorter than the synodic month (29.53 d) because Earth advances ~27° along its orbit in the same period; the Moon must travel further to re-align with the Sun. Used in GPS orbit design, tidal modelling, and lunar laser ranging. 1 sid.mo = 27.3217 d.
About Months
A mean Gregorian calendar month = 365.2425 ÷ 12 = 30.436875 days = 2,629,746 s exactly (averaged over the 400-year cycle with exactly 97 leap years). Individual months have 28-31 days. Loan schedules, subscriptions, and mobile billing reference 'per month', requiring explicit agreement on meaning. ISO 8601 uses 'P1M'. 1 mo = 30.436875 d = 2,629,746 s.
Quick Reference Table
| Sidereal Months (sid.mo) | Months (mo) |
|---|---|
| 1 sid.mo | 0.89765 mo |
| 2 sid.mo | 1.7953 mo |
| 5 sid.mo | 4.48825 mo |
| 10 sid.mo | 8.9765 mo |
| 25 sid.mo | 22.4413 mo |
| 50 sid.mo | 44.8825 mo |
| 100 sid.mo | 89.765 mo |