For example,

60 seconds = 1 minute

60 minutes = 1 hour

24 hours = 1 day

7 day = 1 week

29-31 days = Month (approx.)

365/366 days = year

It's like for the imperial measurement of distance, where 1 mile = 5280 feet...

Edit: just to clarify, I'm more or less keen towards any consistent, decimal-based measurement systems like base-10 or base-12.