Day of Week Calculator
Weekday index = Date(year, month − 1, day).getDay()Date(2026, 7, 6).getDay() = 4; index 4 is Thursday
Free online tool
Day of Week Calculator
Enter a valid calendar date to find its weekday. For example, August 6, 2026 is a Thursday.
Instant calculation
Day of Week Calculator
Enter a year, month and day to find out which day of the week it falls on.
Your result
Calculation
Your numbers stay in this browser. Nothing is uploaded or saved.
Three clear steps
How to use this calculator
- 01
Enter date
Type the year, month and day.
- 02
Calculate
See the day of the week.
- 03
Check historical dates
Check that the date exists; invalid dates such as February 30 are rejected. Historical local calendar transitions are not modeled.
The formula
How this calculation works
The implementation constructs a local JavaScript Date, rejects overflow dates such as February 30, then reads getDay(). Sunday is index 0 and Saturday is index 6. It uses Gregorian calendar rules, including leap years; it does not use Zeller's formula.
Check the method
Worked examples
Each example follows the same formula used by the calculator.
What day is August 6, 2026?
Date(2026, 7, 6).getDay() = 4; index 4 is ThursdayThursdayCommon questions
Questions about this calculation
What is the Day of Week Calculator?
The Day of Week Calculator helps you find the day of the week for any given date. Enter your values and select Calculate to get an instant result.
How is the result calculated?
Calculates the weekday using a calendar algorithm that accounts for leap years and month offsets.
Can you show an example?
Example: What day is August 6, 2026? — Thursday.
Is my data saved when I use the Day of Week Calculator?
No. All calculations run locally in your browser. Your inputs and results are never uploaded, stored or shared with anyone.
Is the Day of Week Calculator free to use?
Yes. The Day of Week Calculator is completely free. No account, sign-up or payment is required. It works on mobile, tablet and desktop.
Continue calculating