Convert Days to Synodic Months
Convert Days (d) to Synodic Months (syn.mo) instantly and accurately.
Conversion Formula
syn.mo = d × 0.03386319199
About Days
A day (d) = exactly 86,400 s. Earth's actual solar day varies ±16 s due to orbital eccentricity and axial tilt (equation of time). Leap seconds (abandoned in UTC after 2035) corrected the TAI-UT1 divergence. Mars's sol = 24 h 39 min 35 s ≈ 88,775 s; a Martian year = 668.6 sols. The day structures circadian biology, tides, and planetary science. 1 day = 86,400 s = 24 h.
About Synodic Months
A synodic (lunar) month = new moon to new moon = 29.5306 days = 2,551,442.9 s. Longer than the sidereal month (27.32 d) because Earth advances ~27° in its orbit during that time; the Moon must travel further to realign with the Sun. Islamic Hijri, Hebrew lunisolar, and Chinese calendars are built on synodic months. Eclipses repeat via the Saros cycle (18 yr 11 d = 223 synodic months). 1 syn.mo ≈ 29.5306 d.
Quick Reference Table
| Days (d) | Synodic Months (syn.mo) |
|---|---|
| 1 d | 0.0338632 syn.mo |
| 2 d | 0.0677264 syn.mo |
| 5 d | 0.169316 syn.mo |
| 10 d | 0.338632 syn.mo |
| 25 d | 0.84658 syn.mo |
| 50 d | 1.69316 syn.mo |
| 100 d | 3.38632 syn.mo |