How to use the Day of the Week Calculator
The day of the week calculator tells you which weekday any date falls on.
Open the Day of the Week Calculator →
What you need to enter
- Date
The formula
It uses the calendar to find the weekday and the day number in the year.
Worked example
Using the default values in the calculator:
- Date: 2026-10-13
| Day of the week | Tuesday |
| Day of the year | 286 |
| Leap year? | No |
Tips for better results
- Useful for birthdays and historical dates.
- Leap years are handled.
Common mistakes to avoid
- Wrong date format.
- Confusing calendar systems.
Please note: Results are estimates for general use. For safety-critical work such as electrical or building projects, check with a qualified professional and local codes. See our Disclaimer.