Day of Week Calculator
Find the weekday of any date, plus day of year, ISO week number, Julian day and month facts. Great for historical dates and event planning.
Use YYYY-MM-DD.
Day of week
Monday
Day of year
222
143 days left in 2026
Week number
33
ISO 8601 week
Julian day
24,61,263
Leap year
No
2026 has 365 days
Month
August
31 days
Weekdays in August 2026
Monday is the 2nd monday of the month.
| Weekday | Occurrences | Weekend? |
|---|---|---|
| Sunday | 5 | Yes |
| Monday (this date) | 5 | No |
| Tuesday | 4 | No |
| Wednesday | 4 | No |
| Thursday | 4 | No |
| Friday | 4 | No |
| Saturday | 5 | Yes |
How it works
Weekday from the Gregorian calendar; day of year = days since Jan 1; Julian day = continuous day count since 4713 BC.
Example: 10 Aug 2026 is a Monday (day of year 222).
Last updated: June 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
Knowing which weekday a date falls on settles real questions in Indian life: whether a wedding date clashes with a working day, when a gazetted holiday creates a long weekend, or which day an old document was executed. This calculator returns the weekday for any date, plus the day-of-year number used in academic calendars and project planning. Families fixing an auspicious date for a ceremony check it against their calendars, and event planners confirm whether a proposed date falls on a weekend before booking halls. The day-of-year output helps teachers and exam boards count teaching days, and the Julian day number serves students and researchers working with historical dates. One date field and the answer appears — no more arguments about what day a holiday falls on.
How to Use This Calculator
- Step 1: Enter any date, past or future, in the date field using the YYYY-MM-DD format.
- Step 2: Read the weekday of that date, shown first in the results.
- Step 3: Read the supporting facts — day of the year, days left in the year, ISO week number and Julian day.
- Step 4: Check the month table to see how many times each weekday occurs in that month, which helps with planning meetings and trips.
Worked Example
Enter 15 June 2026 and the tool returns Monday as the weekday, day 166 of the year with 199 days left, and ISO week number 25. The Julian day number is the continuous count astronomers use to compare dates across centuries. The month table shows June 2026 has 30 days and that Monday and Tuesday each occur 5 times, while the other weekdays occur 4 times. The same lookup works for a grandparent's birth date, an old property deed or an upcoming event you want to place on a weekend.
Tips and Common Mistakes
- •Tip 1: Use the day-of-year figure to compare how far through the year two dates fall, such as a festival that moves between November and December.
- •Tip 2: Check the weekday before planning weekend trips — the tool confirms whether a long weekend forms around a gazetted holiday.
- •Tip 3: The weekday table tells you at a glance how many times a weekday recurs in the month — useful for scheduling a recurring meeting.
- ✗Mistake 1: Assuming the same calendar date repeats the same weekday every year — weekdays shift by one day each common year and two after a leap year.
- ✗Mistake 2: Confusing the Julian day number with the day-of-year count; they are different systems and the numbers are not interchangeable.
Frequently Asked Questions
How do I find what day of the week a date was?
Enter the date and the calculator returns the weekday directly. For example, 15 August 2026 was a Saturday.
What is a Julian day number?
It is a continuous count of days since 1 January 4713 BC, used in astronomy and computing to compare dates without calendars.
What is the day of year?
It is the position of the date within the year — January 1 is day 1 and December 31 is day 365 (or 366 in a leap year).
Do dates and weekdays repeat in a fixed cycle?
Yes. The full cycle of dates and weekdays repeats every 28 years on the Gregorian calendar, which is why old calendars can be reused after 28 years.
Compare these tools
- Age Calculator — Find your exact age in years, months and days from your date of birth
- Date Add Subtract Calculator — Add or subtract days, weeks, months or years to any date, including business days, and see the resulting weekday
- Date Difference Calculator — Count the exact days, weeks, months, years and business days between two dates, with hours and minutes too
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