Day of the Week Calculator

Find what day of the week any date falls on. Works for past, present, and future dates across centuries.

Day of the Week Calculator tool

Loading...

Example

Input: Date 1969-07-20 (Apollo 11 Moon landing)

Result: Sunday - 201st day of 365, ISO Week 29

Jan (31) + Feb (28) + Mar (31) + Apr (30) + May (31) + Jun (30) + 20 days = day 201 of 1969.

  1. Enter any date - historical, current, or future - using the date picker or by typing it into the input field.
  2. View the day of the week (Monday through Sunday) displayed prominently as the primary result.
  3. Check the additional context showing the day number within the year (1-366) and whether the date falls on a weekday or weekend.
  4. See the ISO week number associated with the entered date for cross-referencing with weekly schedules.
  5. Try different dates to check what day your next birthday falls on, verify historical events, or plan future schedules.

What Day of the Week Was It?

Enter any date to see which day of the week it falls on. July 20, 1969, the day of the Apollo 11 Moon landing, was a Sunday. It works for past and future dates. It uses the Gregorian calendar, which most of the world uses today.

Along with the weekday, you get a few handy facts about the date. You see its day number in the year, such as the 201st day of 365, and its ISO week number and quarter. It also says whether the date is a weekend, whether the year is a leap year and how many days are left in the year. A last line tells you how far the date is from today, such as "Tomorrow" or "412 days ago".

People use this to see what day a birthday or holiday falls on this year, to plan events and to check old records. The weekday pattern repeats every 400 years in the Gregorian calendar. Two dates exactly 400 years apart always share a weekday.

One caution for very old dates: the tool uses the Gregorian calendar for every year, even before it was adopted. Many countries changed from the older Julian calendar between 1582 and the 1920s. A date from before the switch in a given country may have had a different weekday there at the time. For the week number on its own, see the Week Number Calculator. To check a leap year, use the Leap Year Checker.

Frequently Asked Questions

Enter your birth date and the weekday shows at the top of the results. For example, anyone born on January 1, 2000 was born on a Saturday. The tool also gives the day number within that year and the ISO week, which can be fun to share on a birthday.
Use an anchor date. Each year, 4/4, 6/6, 8/8, 10/10 and 12/12 all fall on the same weekday, called the doomsday. In 2026 they are all Saturdays. So December 25, 2026, 13 days after 12/12, is a Friday. Then count forward or back in steps of 7.
Yes, but it uses the Gregorian calendar for every date. Britain and its colonies switched from the Julian calendar in 1752, and Russia in 1918. So a date from before the switch in those places may show a different weekday than people used at the time. Historians often mark such dates as Old Style.
Leave the date on today and read the Day of Year line, such as "268th day of 365". September 25, 2026 is day 268. In a leap year, every date after February 28 is one day number higher than it would be in a common year.

Related Tools

Week Number Calculator

Find the ISO week number for any date. See which week of the year a specific date falls in.

Date and Time

Date Difference Calculator

Find the exact number of days, weeks, months, and years between any two dates. Fast and accurate.

Date and Time

Add and Subtract Days from Date

Add or subtract days, weeks, months, or years from any date. Get the resulting date instantly.

Date and Time

Leap Year Checker

Check if any year is a leap year. See the rules explained and find the next or previous leap years.

Date and Time

Age Calculator

Calculate your exact age in years, months, and days from your date of birth. Find age at any past or future date.

Date and Time

Unix Timestamp to Date

Convert Unix timestamps to human-readable dates and vice versa. Supports seconds and milliseconds formats.

Date and Time