Choose any date to find its weekday, day number within the year, remaining days, and the number of matching weekdays already passed and still ahead. A complete Sunday-through-Saturday calendar for the selected month is included.
How to use this calculator
Enter the complete calendar date, including the year. Check the month and day before reading the weekday. For historical dates, confirm which calendar your source uses before comparing it with a modern calendar calculation.
Examples
September 13, 2026
This date is Sunday, day 256 of 365. There are 109 days left, and it is the 37th of 52 Sundays in the year, leaving 15 Sundays.
Formula
Weekdays repeat every seven days. The calculation uses a whole-day UTC index, then applies the Gregorian leap-year rules when counting annual progress.
Calendar scope
The weekday is calculated in the proleptic Gregorian calendar, extending today's leap-year rules backward. Historical places adopted the Gregorian calendar on different dates, so a weekday from a contemporary historical record may differ. The result is a civil-calendar calculation and does not use a time, location, or time zone.