Date Utilities

A countdown is simply the number of days between today and a future date. This tool calculates the difference at midnight (start of day), so a date set for tomorrow will always show 1 day remaining.

A leap year has 366 days (February gets 29 days instead of 28). The rule: divisible by 4, EXCEPT centuries (divisible by 100) are NOT leap years, EXCEPT years divisible by 400 ARE leap years. So 2000 was a leap year, but 1900 was not.

ISO week numbering (ISO 8601) defines weeks as starting on Monday. Week 1 is the week containing the first Thursday of the year. This means January 1 might be in the last week of the previous year, and some years have 53 weeks.