Day Of Year Calculator
Find a date’s day number within its year, accounting for leap years.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Calendar date | Gregorian calendar date in YYYY-MM-DD format; years 0001 through 9999. |
Understanding your result
Calendar results use the stated counting and anniversary convention. Complete months and years differ from fixed day counts.
Common mistakes
- Counting both end dates when the method excludes a boundary, or assuming all months have equal length.
Check your calculation
- Test a short known interval and a leap-day boundary; for working days, verify your holiday list.
Calculation checks, sources and review limits
Which numbered day of the year is this date?
Find a date’s day number within its year, accounting for leap years.
Common uses
- Find a date’s day number within its year, accounting for leap years.
How it works
day=ordinal(date)-ordinal(Jan1)+1 Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
Worked example
Enter Calendar date: 2024-03-01. The result is Day of year: 61.
FAQ
Which numbered day of the year is this date?
day=ordinal(date)-ordinal(Jan1)+1 Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
What assumptions and limits apply?
Inputs and results must stay within the stated supported ranges.