Day of the Week Calculator
Find what day of the week any date in history or the future falls on — plus week number and day-of-year.
Frequently Asked Questions
How is the day of the week determined?
Using JavaScript's Date object, which follows the proleptic Gregorian calendar (projecting the current calendar back in time). For dates before the 1582 Gregorian reform, historical Julian calendars may differ.
What is ISO week number?
ISO 8601 week numbering: weeks start Monday, week 1 contains the first Thursday of the year. Ranges 1-52 or 1-53.