About Time Units
The second (s) is the SI base unit of time. All larger units are derived from it — a minute is exactly 60 seconds, an hour 3,600, and a day 86,400.
Month and year values here use average lengths (30.4375 days/month, 365 days/year) and are approximate.
Pro Tips
There are 1,000 milliseconds in a second — useful when working with APIs and performance timings.
A leap year has 366 days (31,622,400 seconds) — remember to account for this in date calculations.