Translate any calendar date into planning-friendly week, day, and quarter references.
ISO week-
ISO week-year-
ISO weekday-
Day of year-
Calendar quarter-
Days remaining-
This ISO week runs from-
Method
Time and calendar calculation method
Stopwatch elapsed time uses a monotonic high-resolution browser clock. Calendar results use Gregorian and ISO rules, while lunar and solar results apply documented mean-cycle and coordinate formulas.
Astronomical output is an estimate. Coordinates, elevation, refraction, local terrain, the entered UTC offset, and the simplified lunar model can change observed or high-precision event times.
Questions
Week Number Calculator FAQ
Why can January belong to the previous ISO year?
ISO week 1 is the week containing January 4 and weeks begin Monday, so early January dates can fall in the prior ISO week-year.
How many ISO weeks can a year have?
An ISO week-year has 52 or 53 complete weeks depending on its weekday pattern and leap-year status.
