Day of Week Calculator

Weekday, weekend verdict, and quarter for any calendar date.

What it does

Day of week mapping turns any calendar date into its weekday through Gregorian cycle math. Birthdays, anniversaries, and history dates all resolve the same way once the calendar rules run.

The tool above takes one date. It returns the weekday with a weekend or weekday verdict and the calendar quarter beside them.

The default October 10 2026 reads Saturday, Weekend, Q4 2026. Moon landing day July 20 1969 reads Sunday while January 1 2000 reads Saturday, each checkable against records.

Calendar math follows NIST timekeeping practice with time.gov as the public face of official US time. Parsing at UTC noon keeps midnight zone edges from nudging the answer.

How to use

1. Pick any calendar date.
2. Read the weekday first.
3. Use the verdict for weekend planning.
4. Use the quarter for reports and stats.
5. Cross check famous dates against records.

Formula

UTC noon

Parsing point dodging zone edges.

0-6

Sunday to Saturday index.

Q1-Q4

Three month blocks of the year.

Gregorian rules assumed throughout, including century leap exceptions. Proleptic dates before 1582 follow the same math without historical calendar reforms.

Worked example

Reference table

Limits

• Gregorian calendar only throughout.
• No Julian to Gregorian reform modeling.
• Weekends mean Sat/Sun; cultures vary.
• Holidays need their own tables.

Common mistakes

• Reading local midnight dates across zones.
• Assuming pre 1582 dates match old records.
• Calling Friday weekend by habit.
• Mixing week numbers with quarters.
• Trusting memory over the calendar for old birthdays.

Try it yourself

Quick checks. Answers sit tucked under each question.

Questions

Sources

• NIST: time and frequency
• time.gov: official US time

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