Julian Day Calculator
Calculate the Julian Day Number (JDN) for a selected calendar date.
Calculator
Results
How it works
Calculate the Julian Day Number (JDN) for a selected calendar date.
Example
| Example | Result |
|---|---|
| Jan 15, 2026 has JDN 2461056. | See calculator |
Important notes
- Calendar calculations use Gregorian calendar rules.
- Business-day calculations exclude Saturday and Sunday unless stated otherwise.
- Time-zone calculations depend on the browser's IANA time-zone data.
- For planning purposes, verify dates and times when a contractual or legal deadline is involved.
Frequently Asked Questions
Is JDN the same as Julian Date?
JDN is an integer day number; Julian Date can include a fractional part for time of day.
How to use this calculator
What to enter
Enter or select the following as requested: Date. Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The date or duration result is calculated from the entered dates, times, calendar rules, and exclusions. Check inclusive versus exclusive counting, time zone, daylight-saving changes, and whether weekends or holidays are excluded.
When to use it
Use this to plan a date, measure elapsed time, or estimate a deadline. Verify the relevant calendar, location, and legal or workplace rules when they affect the answer.