Day of Year Calculator

This tool converts between a calendar date and its position in the year, in both directions. Give it a year, month and day and it returns the day number, how many days are left, how much of the year has gone by, the quarter, the ISO week date and the Julian day number; give it a year and a number from 1 to 366 and it returns the date. January 1 is day 1, so the count includes the date itself. Only Gregorian years from 1583 onward are accepted, because the day each country adopted that calendar was different.