The second is the SI base unit of time, defined since 1967 by exactly 9,192,631,770 cycles of caesium-133 atom radiation. Atomic clocks based on this definition are so precise they would not gain or lose a single second over 300 million years — they form the backbone of GPS satellite timing, internet synchronisation (NTP), and financial transaction timestamps.
Larger time units have irregular lengths rooted in ancient history. The 60-second minute and 60-minute hour derive from the Babylonian base-60 (sexagesimal) number system, chosen for its many divisors. Months and years are tied to lunar and solar cycles, creating calendar complexity. This converter uses the average Gregorian year (365.2425 days = 31,556,952 seconds) and the average month (30.4369 days = 2,629,746 seconds).
| 1 minute | = 60 s |
| 1 hour | = 3,600 s |
| 1 day | = 86,400 s |
| 1 week | = 604,800 s |
| 1 year (avg) | ≈ 31,556,952 s |
| 1 month (avg) | ≈ 2,629,746 s |