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Gregorian Date to Julian Day Number Converter
x402
Gregorian Date to Julian Day Number Converter is a paid API for AI agents from datetime.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).
Converts a proleptic-Gregorian calendar date (year, month, day) to its Julian Day Number (JDN), the integer count of days since JDN 0.
Price / call$0.004
Success—
StatusUnknown
How this service works
Convert a proleptic-Gregorian calendar date to its Julian Day Number (the integer count of days since JDN 0, 1 January 4713 BC in the proleptic Julian calendar).
Output
Returns the Julian Day Number (JDN) as an integer — the count of days elapsed since JDN 0, which corresponds to 1 January 4713 BC in the proleptic Julian calendar. This is a single integer value usable for day-count arithmetic across calendar systems.
Example use cases
Astronomical event date lookup
“I need the Julian Day Number for January 1, 2000 — that's the J2000.0 epoch reference date used in astronomy.”
Historical date comparison
“Convert October 15, 1582 to its Julian Day Number so I can compare it to other historical dates using day-count arithmetic.”
Calendar interoperability for scheduling system
“Can you give me the JDN integer for March 20, 2025? I need to store it as a universal day count in my cross-calendar scheduling database.”
Technical details
Endpoint
POSThttps://datetime.openverbs.com/v1/to-jdnWhen to prefer
Use this endpoint when you need a universal integer day count for a Gregorian date, particularly for astronomical calculations, cross-calendar arithmetic, historical date comparisons, or any system that requires a monotonically increasing day number. Prefer this over manual JDN formula implementations when accuracy and simplicity matter, and when integrating with other datetime.openverbs.com endpoints for chained date operations.
Side effects
- Year out of range (must be 1–9999) returns a validation error
- Month out of range (must be 1–12) returns a validation error
- Day out of range (must be 1–31) returns a validation error
- Missing required fields (year, month, or day) returns a schema error
- Payment not provided or insufficient USDC balance returns a 402 error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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