Day of the YearFree online date & time calculator — instant results, no sign-up
See which day of the year a date is, and how many days remain.
About the Day of the Year
The Day of the Year calculator shows a date’s numbered position within its year and how many calendar days remain afterward. For 2026-10-23, it reports day 296, with 69 days remaining in a 365-day year.
- Date
- The calendar date to evaluate, entered as year-month-day (YYYY-MM-DD), with a default of 2026-10-23 and day-level precision.
Formula and method
D = d + Σ(i = 1 to m − 1) Lᵢ(y); Y = 365 + ℓ(y); R = Y − D. Here ℓ(y) = 1 if y is divisible by 400, or divisible by 4 but not by 100; otherwise ℓ(y) = 0. For 2026-10-23: D = 23 + 273 = 296; Y = 365; R = 365 − 296 = 69.
- yYear of the selected date.
- mMonth number of the selected date.
- dDay of the month of the selected date.
- iMonth index used to sum the months before the selected month.
- Lᵢ(y)Number of calendar days in month i of year y, accounting for February in leap years.
- ℓ(y)Leap-year indicator: 1 for a Gregorian leap year and 0 otherwise.
- DDay of year, counting January 1 as day 1.
- YTotal number of calendar days in the selected year.
- RCalendar days remaining after the selected date through December 31.
Determine whether the selected year is a Gregorian leap year, then use the corresponding month lengths. Add the days in all completed months to the selected day of the month to obtain the day of year. Subtract that result from the year’s total length to find the days remaining. For 2026-10-23, January through September total 273 days; adding 23 gives 296, and subtracting 296 from 365 gives 69.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Date1970-01-01
Results
- Day of year1
- Days remaining in year364
- Year length365 days
How to use the Day of the Year
- 1Enter or select the Date; keep 2026-10-23 to reproduce the worked example.
- 2Check that the year, month, and day match the date you intend to evaluate.
- 3Read Day of year: the default date is day 296.
- 4Read Days remaining in year: 69 calendar days follow the default date before the year ends.
- 5Check Year length: 365 days confirms that 2026 is not a leap year.
Reading your result
Day of year is a one-based count that includes the selected date, so 296 means 2026-10-23 is the 296th calendar day of 2026. Days remaining in year excludes the selected date and includes December 31, so 69 days remain after October 23. Year length is the total number of calendar days in that year: 365 for the default date’s year.
Limitations
The calculation assumes the Gregorian calendar and a valid calendar date. It counts all calendar days, including weekends and holidays, rather than business days. It does not measure hours remaining or account for time of day, time zones, daylight saving changes, or leap seconds. Historical dates interpreted under other calendars may have different day-of-year values.
Common questions
Does Days remaining in year include the selected date?+
No. For 2026-10-23, the 69 remaining days run from the following day through December 31. The selected date is included in Day of year instead.
Why is 2026-10-23 day 296?+
The months January through September contain 273 days in 2026. Adding October’s day-of-month value, 23, gives 296.
How does a leap year affect the results?+
A leap year has 366 days and February has 29 days. For the same month and day after February, the day-of-year number is one higher than in a common year. The calculator uses the Gregorian divisibility rules to determine this automatically.
Does the day-of-year count start at zero or one?+
It starts at one: January 1 is day 1. December 31 equals the year length and has zero days remaining afterward.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.