What Is the Day of the Week Calculator?
Day of the week determination computes the cyclical 7-day name for historical or future dates.
How Does the Day of the Week Calculator Work?
Evaluates Gregorian calendar leap year periodicity and ISO day-of-year accumulation.
Day of the Week Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
h = \left(q + \left\lfloor\frac{13(m+1)}{5}\right\rfloor + K + \left\lfloor\frac{K}{4}\right\rfloor + \left\lfloor\frac{J}{4}\right\rfloor - 2J\right) \bmod 7
Uses calendar day indexing to determine weekday and leap year status.
How to Use the Day of the Week Calculator
- Enter the year, month, and day of the month.
Step-by-Step Example Calculation
Find Day for October 6, 2026
Input Values:
year:2026
month:10
day:6
Worked Steps: October 6, 2026 falls on a Tuesday.
Understanding Your Result
Returns the weekday name, day of the year, ISO week number, and leap year confirmation.
Factors That Affect the Result
- Julian to Gregorian calendar transition in October 1582.
When Should You Use This Calculator?
- Historical event verification, planning future celebrations, and checking day of birth.
Assumptions & Limitations
- Applies standard proleptic Gregorian calendar conventions.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Gregorian calendar astronomical definition.