Quick Reference - Popular Time Conversions
| From | To | Operation | Example |
|---|---|---|---|
| seconds | minutes | ÷ 60 | 120 sec = 2 min |
| minutes | seconds | × 60 | 5 min = 300 sec |
| minutes | hours | ÷ 60 | 90 min = 1.5 hr |
| hours | minutes | × 60 | 2.5 hr = 150 min |
| hours | days | ÷ 24 | 48 hr = 2 days |
| days | hours | × 24 | 3 days = 72 hr |
| days | weeks | ÷ 7 | 14 days = 2 wk |
| weeks | days | × 7 | 4 wk = 28 days |
| days | years | ÷ 365.25 | 365 days ≈ 1 yr |
| years | days | × 365.25 | 2 yr = 730.5 days |
Key Time Equivalents
| Duration | Seconds | Minutes | Hours | Days |
|---|---|---|---|---|
| 1 minute | 60 | 1 | 0.0167 | 0.000694 |
| 1 hour | 3,600 | 60 | 1 | 0.0417 |
| 1 day | 86,400 | 1,440 | 24 | 1 |
| 1 week | 604,800 | 10,080 | 168 | 7 |
| 1 month (avg) | 2,629,746 | 43,829 | 730.5 | 30.44 |
| 1 year (avg) | 31,557,600 | 525,960 | 8,766 | 365.25 |
Understanding Time Units
Where Base-60 Comes From
Time runs on base-60 (sexagesimal), a system from ancient Babylon about 4,000 years ago. The Babylonians picked 60 because it divides cleanly by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30—useful when doing math without a calculator. That's where 60 seconds per minute and 60 minutes per hour come from.
Why 24 Hours in a Day?
Ancient Egyptians came up with the 24-hour day around 1500 BCE. They split daylight into 10 hours, added twilight hours at dawn and dusk, then mirrored that for night. Why base 12? One theory is finger-joint counting—three joints per finger times four fingers.
Why Months and Years Don't Fit Neatly
Months and years don't divide neatly into days—Earth's orbit takes about 365.2422 days, the Moon's about 29.53. No calendar solves this perfectly. The Gregorian calendar averages it out: months run 30.4375 days (365.25 ÷ 12), and the 365.25-day year bakes in leap years. This still drifts from Earth's true orbit by about 26 seconds annually.
How Scientists Define a Second
The second is the base unit of time because it can be pinned to atoms. Since 1967, one second has been defined as 9,192,631,770 oscillations of cesium-133. Atomic clocks using this definition lose less than a second over 300 million years.
Precise Definitions Used in This Converter
- Average month: 30.4375 days, which is 365.25 ÷ 12
- Average year: 365.25 days to account for leap years
- Calendar year: 365 days flat
- Leap year: 366 days
- Julian year: 365.25 days exactly—the standard in astronomy
- Gregorian year: 365.2425 days, a slightly more accurate average