Find which day of the week any date falls on, plus the day of the year and ISO week number. Enter the year, month, and day.
Usage Tip
Useful for scheduling: check which weekday a future date lands on before planning around it.
Day of year and ISO week number follow from it.
ISO week numbering starts weeks on Monday and assigns week 1 to the week containing the first Thursday of the year.
ISO week can be 52 or 53 depending on the year.
Leap years (shown here) have 366 days, adding Feb 29.
Every date falls on a specific day of the week, and it can be found for any year past or future. The calculator also shows the day of the year, counting January 1 as day 1, and the ISO week number, which numbers the weeks of the year starting with the week that contains the first Thursday.
ISO weeks begin on Monday, and the first and last days of a year can belong to a week of the neighboring year. The day of the year is handy for scheduling, agriculture, and engineering logs. A year is a leap year if it is divisible by four, except for century years, which must be divisible by 400, so 2000 was a leap year but 1900 was not.