Day of Year Calculator
Pick a date to see which day of the year it is and how many days are left in that calendar year — leap years handled automatically.
How this is calculated
The day-of-year number is the count of calendar days from January 1st of that year up to and including your chosen date, computed as the days between January 1st and your date, plus one. Days remaining is the year's total length — 365 days, or 366 in a leap year — minus that day-of-year number. The total is never hardcoded to 365: it's derived from a leap-year check on the specific year of your chosen date, so results stay correct for any year you pick, past or future.
Frequently asked questions
Does January 1st count as day 1 or day 0?
Day 1. The calculator counts the calendar days from January 1st up to and including your chosen date, so January 1st itself is always day 1 of the year.
How do leap years affect the day-of-year count?
In a leap year, February gains a 29th day, which pushes every date from March 1st onward one day later in the year's numbering than the same calendar date in a non-leap year. December 31st is day 365 in a normal year but day 366 in a leap year — the calculator checks the year's leap status automatically rather than assuming 365.
How is "days left in the year" computed?
It's the year's total day count (365, or 366 in a leap year) minus the day-of-year number for your chosen date. The total is derived from a leap-year check for that specific year, not hardcoded, so the figure is correct whether or not the year has a February 29th.