Julian Date Converter
Convert a calendar date into all seven Julian formats: Day of Year, 4-digit YJJJ, 5-digit YYDDD, 7-digit YYYYDDD, Julian Day Number (JDN), astronomical Julian Date (JD), Modified Julian Date (MJD), and ISO 8601. Reverse any Julian value back to a calendar date, then batch-convert common date lists when you need more than one answer.
New to these codes? See the Julian date overview, the seven formats explained, or the batch decoder.
Live Reference
26207
Sunday, July 26, 2026
Use these live values as a quick reference before converting another date, code, or Julian Date value.
Current Snapshot
Common Julian date: 26207. YJJJ: 6207. Full ordinal: 2026207. Day of year: 207. JDN: 2461248. JD: 2461247.50034. MJD: 61247.00034.
Day-of-year codes
Day Of Year
207
YJJJ
6207
YYDDD
26207
YYYYDDD
2026207
Astronomical
JDN
2461248
JD
2461247.50034
MJD
61247.00034
Convert a Calendar Date to Julian Formats
Use this section when you start with a normal calendar date. The common Julian codes come from the date itself. The astronomical outputs use the selected time basis so you can work with an exact instant when needed.
Converted Result
Select a date and time to calculate every Julian format.
Day Of Year
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YJJJ (4-digit)
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YYDDD (5-digit)
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YYYYDDD (7-digit)
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JDN
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JD
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MJD
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ISO 8601
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The common codes reflect the calendar date. The astronomical outputs reflect the selected time basis and clock time.
Convert a Julian Value Back to a Calendar Date
Paste any Julian code such as YJJJ, YYDDD, or YYYYDDD, or enter a Julian Day Number (JDN), astronomical JD, or MJD value. The 4-digit YJJJ format is ambiguous, so pick the matching decade. If you use a plain day-of-year number such as 161, choose the year that should be applied.
Converted Result
Enter a Julian value to convert it back to a date.
Detected Type
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Calendar Date
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ISO 8601
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Day Of Year
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YJJJ
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Common YYDDD
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Full YYYYDDD
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JDN
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JD
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MJD
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For JDN, JD, and MJD values, the converter also resolves the UTC instant. For DDD-only input, the year field is required, and for YJJJ input the decade selector resolves the ambiguous year.
Batch Convert Common Julian Codes
Convert multiple date-only values at once. This batch section focuses on the common day-of-year style Julian formats, which are the most useful for labels, spreadsheets, production logs, and everyday operational work.
Expected date input is one YYYY-MM-DD value per line. Supported Julian input is one YJJJ, YYDDD, YYYYDDD, or DDD value per line. YJJJ codes use the selected decade.
Supported Formats
Day of Year: a 1 to 366 ordinal day count, the basis of every common code.
YJJJ: a 4-digit consumer batch code such as 6099, with a single year digit. Ambiguous across decades, so pick the decade.
YYDDD: a 5-digit common business code such as 26161.
YYYYDDD: a 7-digit full year code such as 2026161.
DDD: a day-of-year number from 1 to 365 or 366. The year must be provided separately.
JDN: the integer Julian Day Number, referenced to noon UTC, such as 2461140.
JD: the astronomical Julian Date, a continuous fractional count tied to an exact instant.
MJD: Modified Julian Date, equal to JD minus 2400000.5.
When to Use the Calendar Instead
If you want to browse the whole year visually instead of converting one value at a time, open the Julian date calendar.
The calendar page is built for current-year and adjacent-year browsing, while this page is built for exact conversions and batch work.
If you only need the broad answer for today, the main Julian date page is the simpler entry point.
For full definitions of every code, read the seven Julian formats explained, or decode a list of packaging codes with the batch decoder.