Weekday Calculator
Find the day of the week for a past or future Gregorian calendar date.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Calendar date | Gregorian calendar date in YYYY-MM-DD format; years 0001 through 9999. |
Understanding your result
Calendar results use the stated counting and anniversary convention. Complete months and years differ from fixed day counts.
Common mistakes
- Counting both end dates when the method excludes a boundary, or assuming all months have equal length.
- Assuming the ISO week-year always equals the calendar year.
Check your calculation
- Test a short known interval and a leap-day boundary; for working days, verify your holiday list.
Calculation checks, sources and review limits
What day of the week was or will this date be?
Find the day of the week for a past or future Gregorian calendar date.
Common uses
- Find the day of the week for a past or future Gregorian calendar date.
How it works
Compute Gregorian ordinal modulo seven, with 0001-01-01 Monday. Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
Worked example
Enter Calendar date: 2024-02-29. The result is Weekday: Thursday.
FAQ
What day of the week was or will this date be?
Compute Gregorian ordinal modulo seven, with 0001-01-01 Monday. Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
What assumptions and limits apply?
Date-only calculation.