Day of Year Calculator
Find out which day of the year (1–366) any date falls on. Free, instant, and calculated right in your browser.
Find out exactly which numbered day of the year any date falls on, handy for payroll and billing cycles that run on Julian dates, fiscal-year planning, or just settling the "what day number is it today" question.
How to use it
- Pick a date, or leave it on today
- Instantly see its day-of-year number
- Enter a day number instead to convert it back to a calendar date
Frequently asked questions
- How is day 1 counted?
- January 1st is day 1, so the day-of-year number always matches the date in January and climbs from there. December 31st is day 365, or 366 in a leap year.
- Does it account for leap years?
- Yes. Enter any year and the tool checks whether it's a leap year and adjusts the count after February 28th accordingly.
- Can I look up a day number for a past or future date, not just today?
- Yes. Pick any date on the calendar and it converts instantly both ways: date to day-of-year number, and day-of-year number back to a calendar date.
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Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
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No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
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Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.