Convert Sidereal Days to Months
Convert Sidereal Days (sid.d) to Months (mo) instantly and accurately.
Conversion Formula
mo = sid.d × 0.03276517599
About Sidereal Days
A sidereal day = Earth's rotation period relative to the stars = 23 h 56 min 4.0905 s = 86,164.0905 s - ~3 min 56 s shorter than the 24 h solar day because Earth advances ~1° in its orbit each day. Equatorial telescope mounts rotate at one turn per sidereal day to track stars. VLBI, GPS orbit determination, and polar-motion monitoring use sidereal rotation as their reference. 1 sid. day = 86,164.0905 s.
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 Days (sid.d) | Months (mo) |
|---|---|
| 1 sid.d | 0.0327652 mo |
| 2 sid.d | 0.0655304 mo |
| 5 sid.d | 0.163826 mo |
| 10 sid.d | 0.327652 mo |
| 25 sid.d | 0.819129 mo |
| 50 sid.d | 1.63826 mo |
| 100 sid.d | 3.27652 mo |