Can I look up dates far in the past?

Yes, from year 1 to 9999. Note that the Gregorian calendar is projected backwards throughout, while countries adopted it at different times, so treat dates before 1582 with that caveat in mind.

Why does the week start on Sunday?

The calendar grid uses the Sunday-first convention common in Taiwan and the United States. For the ISO 8601 Monday-first week and its week numbering, use the week number calculator.

DATE AND TIME · CALCULATED IN YOUR BROWSER

Day of the Week Calculator

Find what weekday any date falls on, with the surrounding month laid out.

Input

Date

January 2026

SunMonTueWedThuFriSat

About this tool

Enter any date and see immediately which weekday it falls on, along with a full calendar of that month so the surrounding days are visible at a glance. Historical and future dates both work; the weekday is derived directly from the calendar rather than from a browser Date, so there is no chance of an off-by-one across midnight.

How it works

Enter the date you want to look up.
Read the weekday and the month calendar.
Click another day in the calendar to look that one up.

Assumptions

Uses the proleptic Gregorian calendar from year 1 to 9999 and is unaffected by the browser time zone.

Privacy

Every calculation runs inside this browser. Dates and birthdays are never uploaded, stored, or written to the URL or any log.

Frequently asked questions

Can I look up dates far in the past?: Yes, from year 1 to 9999. Note that the Gregorian calendar is projected backwards throughout, while countries adopted it at different times, so treat dates before 1582 with that caveat in mind.
Why does the week start on Sunday?: The calendar grid uses the Sunday-first convention common in Taiwan and the United States. For the ISO 8601 Monday-first week and its week numbering, use the week number calculator.

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