🌞 Day of the Year Calculator
Enter any date to find out which numbered day of the year it is, and how much of the year has passed.
What this calculator does
The Day of the Year Calculator finds which numbered day of the year any given date falls on (from 1 to 365, or 366 in a leap year), along with how many days remain and what percentage of the year has already passed.
How the calculation works
The calculator counts the number of days between January 1st of the chosen year and the date you entered, adding 1 so that January 1st itself is day 1. It checks whether the year is a leap year using the standard rule (divisible by 4, except century years unless also divisible by 400) to determine whether the year has 365 or 366 days total.
This tool is for general and educational reference, such as scientific data logging, agricultural planning, or scheduling that uses day-of-year (Julian day) numbering.