Day of Year Calculator
See the ordinal day number (1 to 365, or 366 in a leap year), the ISO week number, days remaining and the percentage of the year already gone.
Pick a date to see its day number.
How to use
- Pick a date to see its day number, week number and days left in that year.
- Or type a day number (1 to 366) to find which date it falls on in the selected year.
Day numbers count from 1 January as day 1. Week numbers follow ISO 8601, where week 1 is the week containing the first Thursday of the year.
Frequently Asked Questions (FAQ)
What does the day of year calculator show?
For any date it shows the ordinal day number (1 to 365, or 366 in a leap year), the ISO week number, days remaining in the year, and the percentage of the year already gone.
Can I find a date from a day number?
Yes. Type a day number from 1 to 366 and the tool finds which date it falls on in the selected year.
What is an ISO week number?
Weeks follow ISO 8601, where week 1 is the week with the first Thursday of the year and weeks start on Monday.
Does it handle leap years?
Yes. In a leap year the day numbers run to 366, and 29 February counts as day 60.