Day of the Week Calculator
Find what day of the week any date falls on, past or future.
A day of the week calculator determines what day any date falls on, along with the week number, day of the year, zodiac sign, and season.
Examples
US Independence Day 2024
New Year 2025
Frequently Asked Questions
How often does a date fall on the same day of the week?
What is ISO week numbering?
Quick Tips
- •Use this to plan events, check what day your birthday falls on, or verify historical dates.
- •The Gregorian calendar repeats every 400 years (146,097 days = exactly 20,871 weeks).
- •January 1 falls on each day of the week with varying frequency over a 400-year cycle.
A day of the week calculator determines what day any date falls on, along with the week number, day of the year, zodiac sign, and season.
How to Use This Calculator
Enter any date to find out what day of the week it falls on. The calculator also shows the day of the year, week number, zodiac sign, season, and other interesting facts.
Understanding the Formula
The day of the week is calculated using the Gregorian calendar rules. The calculator also uses modular arithmetic to determine week numbers and day-of-year positions.
Examples
US Independence Day 2024
July 4, 2024 falls on a Thursday. It is the 186th day of the year in a leap year.
New Year 2025
January 1, 2025 falls on a Wednesday. It is the 1st day of the year (not a leap year).
Frequently Asked Questions
How often does a date fall on the same day of the week?
Non-leap years shift by 1 day (if Jan 1 is Monday, next year it is Tuesday). Leap years shift by 2 days. The calendar repeats exactly every 400 years.
What is ISO week numbering?
ISO 8601 defines week 1 as the week containing the first Thursday of the year. Weeks start on Monday. Some years have 52 weeks, others have 53.
Assumptions & Limitations
- Based on the Gregorian calendar; does not handle historical calendar systems.
- Leap years are accounted for in all date calculations.
- Seasons are based on the Northern Hemisphere; Southern Hemisphere seasons are reversed.