Look up the weekday for a date in the past.
Tool · Last updated May 14, 2026
What Day Was It?
Useful for historical checks, records, and timeline validation.
It uses the same weekday engine as the day-of-week calculator, but it is framed for past dates.
Monday
It uses the same weekday engine as the day-of-week calculator, but it is framed for past dates.
Result
Run the tool to see the answer here.
Quick take
Look up the weekday for a date in the past.
How it works
Three quick actions, no wall of instructions.
Enter the value
Type one date or year.
Read the answer
The result appears in the output panel.
Keep it handy
Use it as a quick reference or validation check.
Sample input
Sample output
Monday
Gotchas
Using the result without checking the edge case you care about.
Skipping holiday or daylight-saving checks when the deadline crosses one.
Sending a shared plan before confirming the exact date and time.
Quick answers
Short answers for the edge cases people usually ask about.
What is this for?
A fast calendar reference.
Should I trust it blindly?
Confirm leap-year, week-rule, or calendar edge cases when they matter.
When should I cross-check it?
Before you share a deadline or planning note.