Day of Week Calculator
Last updated: November 5, 2026
Find the weekday, day of year, ISO week and remaining days for a calendar date.
Day of the week
—
- Day of the year: —
- ISO week number: —
- Days remaining in the year: —
On this page
Quick summary: Find the weekday, day of year, ISO week and remaining days for a calendar date.
Read the complete guide
Updated reference sections in this guide are in English.
What this calculator estimates
Find the weekday, day of year, ISO week and remaining days for a calendar date.
How to use it
Enter Year; Month; Day. Select Calculate to update the results.
How the calculation works
The weekday uses the Gregorian calendar, while the ISO week follows the week containing Thursday convention.
Worked example: starting scenario
| Year | 2026 |
|---|---|
| Month | 7 |
| Day | 25 |
| Day of the week | Saturday |
|---|---|
| Day of the year | 206 |
| ISO week number | 30 |
| Days remaining in the year | 159 days |
Important limitations
Dates use the proleptic Gregorian calendar and UTC to avoid local daylight-saving shifts.
Calendar labels are independent of local clock time
The date is treated as a calendar day in UTC for this calculation, so changing your device’s time zone should not shift the weekday. February 29 is accepted only in a leap year. The date system is the Gregorian calendar in the supported year range; historical local calendar reforms or holiday observance are outside the weekday result.