Date & Time
Instant, private, and free
Day of the Week Calculator.
Find what day of the week any date falls on — past, present or future — in your own language.
Set your values
Results update as you type.
Breakdown
How to Use
FAQs
What day of the week was I born on?
Enter your date of birth into the date field and the calculator shows the weekday immediately, along with the ISO weekday number and whether it was a weekend.
What is the ISO weekday number?
ISO-8601 numbers weekdays Monday = 1 through Sunday = 7. JavaScript and many spreadsheets instead use Sunday = 0 through Saturday = 6. This calculator shows both so you can match whichever system your software uses.
Does the calculator work for dates before 1900?
Yes. It handles dates before 1970 and even years below 100 correctly. It uses the proleptic Gregorian calendar, so results match standard software date functions rather than the Julian calendar historically used before 1582.
Will the weekday name show in my language?
Yes. The weekday name is generated from your selected site language using the browser's internationalization support, so it appears in your own language and script rather than always in English.
Which dates count as the weekend?
This calculator labels Saturday and Sunday as the weekend, the most common convention. Some countries use Friday-Saturday or a different pairing, so adjust for your local working week.
Cite this calculator
Canonical URL: https://mathify.one/en/date/day-of-week
Cite as: Mathify. (2026). Day of the Week Calculator. https://mathify.one/en/date/day-of-week
Use Cases
Historical Date Reference
Quickly find out what day of the week a historical event occurred, useful for genealogy, research, or satisfying curiosity.
Example: Find the weekday for July 20, 1969 (Apollo 11 landing).
Planning and Scheduling
Determine the weekday for future dates to plan events, meetings, or personal schedules, especially when you need to know if a date falls on a weekend.
Example: Check what day of the week your birthday falls on next year.
Frequently Asked Questions
- How does the Day of the Week Calculator work?
- Simply enter any date in the provided field, and the calculator instantly determines the corresponding day of the week. It works for both past and future dates, using a reliable algorithm to compute the weekday.
- Can I see the weekday in different languages?
- Yes, the calculator offers localized weekday names in 28 languages. After entering your date, you can select your preferred language to see the day of the week translated accordingly.
- Does it work for dates far in the past or future?
- Yes, the calculator is designed to handle a wide range of dates, both in the past and future. It accurately computes the weekday for any given date you enter.
Tips & Common Mistakes
Tips
- Use the language selector to view weekday names in your preferred language among the 28 supported options.
- Double-check the date format (e.g., MM/DD/YYYY vs DD/MM/YYYY) to ensure accurate results.
- For quick reference, use the calculator to verify the weekday of important dates like anniversaries or holidays.
- Remember that the calculator works for both past and future dates, so you can plan ahead or look back with ease.
Common Mistakes to Avoid
- Entering the date in the wrong format, such as using slashes when the calculator expects dashes, or mixing day and month order.
- Assuming the calculator only works for recent dates; it actually supports a wide range of past and future dates.
- Forgetting to select the desired language if you need the weekday in a specific language other than the default.
Last updated: August 13, 2026