Julian date calculator

JD2461332.00000000 · MJD61331.50000000 · 2026-10-18T12:00:00.000Z.

A continuous astronomical day count

JD advances by one each24 hours and changes its integer at12:00UTC. Modified Julian Date is JD minus2,400,000.5, so its integer changes at midnight. Dates use the proleptic Gregorian calendar; this converter uses UTC and does not relabel the input as Terrestrial Time.

Convert a UTC date and time to astronomical Julian Date and Modified Julian Date, or convert a Julian Date back to UTC.