Convert Date to Day Number in Year
Easily determine the day number in the year for any date, including today; Also shows days left in year, and day of week.
Calculate day number for today, tomorrow, or past and future dates. Simply enter the date above, and find out the date's day number in the specified year, as well as how long until the end of that year.
The calculation is based on the fact that day number 1 of any year is January 1st. Consequently, you may be wondering if a given date (based on month and day) are the same every year? Yes and No! Up until February 28 of any year, day number is always the same. And that's where it can start to differ!
If it's a non-leap year, the year has 365 days since February of non-leap years has 28 days. If it's a leap year, the year has 366 days since February of leap years has 29 days. Consequently, in non-leap years, the day numbers for all 365 days will always be the same. However, for leap years, from February 29 until the end of that year, the day numbers will differ by 1 day from those in non-leap years.
As examples, in a non-leap year, March 1 will be day number 60, but in a leap year it will be day number 61. And, December 31 of non-leap years is day 365, whereas for leap years it is day 366.