Instant · Precise · Universal
28 units available
6 categories total
To convert months to days: multiply by 30.44 (average). To convert to weeks: multiply by 4.35 (approximate).
1 average month ≈ 30.44 days ≈ 4.35 weeks ≈ 730.5 hours ≈ 2,629,800 seconds.
For example, 1 Month (Average) (mo) = 0.08333188161 Year (Sidereal) (yr (Sid)).
| Month (Average) (mo) | Year (Sidereal) (yr (Sid)) |
|---|---|
| 0.1 | 0.008333188161 |
| 0.5 | 0.04166594081 |
| 1 | 0.08333188161 |
| 2 | 0.1666637632 |
| 5 | 0.4166594081 |
| 10 | 0.8333188161 |
| 25 | 2.08329704 |
| 50 | 4.166594081 |
| 100 | 8.333188161 |
| 500 | 41.66594081 |
| 1000 | 83.33188161 |
The average month is a unit of time equal to approximately 30.44 days (2,629,800 seconds), representing 1/12 of a Gregorian calendar year.
1 average month ≈ 30.44 days ≈ 4.35 weeks ≈ 730.5 hours ≈ 2,629,800 seconds.
To convert months to days: multiply by 30.44 (average). To convert to weeks: multiply by 4.35 (approximate).
Billing cycles, rent payments, project milestones, medication tracking, and age calculations (especially for infants).
The mnemonic '30 days hath September' dates to the 13th century. February's 28 days result from Augustus taking a day for August from February.
Treating all months as 30 days. For precise calculations, always account for actual month lengths.
The knuckle trick: make fists, count across knuckles (bumps = 31 days, valleys = 30 or fewer). Start with January on the first knuckle.
The sidereal year is the time for Earth to complete one orbit relative to the fixed stars — approximately 365.25636 days (31,558,149.7632 seconds).
1 sidereal year ≈ 365.25636 days ≈ 365 d 6 h 9 min 10 s. About 20 min 24 s longer than the tropical year.
To convert sidereal years to days: multiply by 365.25636. To tropical years: multiply by 365.25636/365.24219.
Tracking stellar positions, calculating satellite orbital decay, and determining long-term star catalog corrections.
The ~20-minute difference between sidereal and tropical years is caused by axial precession — Earth's axis traces a full circle every ~25,772 years.
Using sidereal year when tropical year is intended (or vice versa) in calendar calculations.
Think of it this way: the sidereal year measures Earth's orbit relative to stars. The tropical year measures relative to seasons. Precession makes them differ.



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