Day of the Week Calculator
Find out which day of the week any date falls on, plus its week number, day of the year and leap year status.
- Day of the week
- Sunday
- Date
- Sunday, October 4, 2026
- ISO week number
- Week 40 of 2026
- Day of the year
- 277 of 365
- Days left in the year
- 88
- Is 2026 a leap year?
- No
What is Day of the Week Calculator?
Knowing the weekday of a past or future date helps with birthdays, history questions, planning and settling arguments.
What this tool does
Takes a date and shows the weekday, the ISO week number, the day of the year, how many days are left in the year, and whether the year is a leap year.
How to use it
- Pick a date, or leave it empty for today.
- Read the weekday and the other details.
- Try another date.
Did you know?
- Under the ISO system weeks start on Monday and week 1 is the week with the first Thursday of the year.
- A year is a leap year if it divides by 4, except years divisible by 100 unless they also divide by 400.