Day of Week Calculator

How the Day of Week Calculator Works

The tool interprets the selected calendar date as a local calendar day (midnight → midnight) and returns the corresponding weekday name (Monday–Sunday). Conversions are performed entirely in the browser using standard date APIs to ensure fast, private results.

Common Use Cases

• Planning: quickly check what weekday a future date falls on for scheduling and deadlines.
• Events & records: confirm weekdays for birthdays, anniversaries, historical events or legal documents.
• Workflows: avoid setting deadlines on weekends or public holidays (combine with business-days tools).
• Education: teach calendar arithmetic or verify answers in exercises.

Examples (copy/paste)

Developer snippets (JS / Python / SQL)

Short examples to compute weekday programmatically (local calendar interpretation).

// Interpret "2026-02-20" as local date and get weekday
const d = new Date("2026-02-20T00:00:00");
const weekday = d.toLocaleDateString(undefined, { weekday: 'long' });
console.log(weekday); // e.g., "Friday"

from datetime import datetime
d = datetime.strptime('2026-02-20', '%Y-%m-%d').date()
print(d.strftime('%A'))  # e.g., "Friday"

-- date → weekday
SELECT to_char(date '2026-02-20', 'Day'); -- returns weekday name

=TEXT(DATE(2026,2,20),"dddd")  -- returns weekday name

Historical notes & accuracy

For modern dates the Gregorian calendar rules are used (the calendar in general use today). For historical dates before the Gregorian adoption (varied by country around 1582–1920s), weekday calculations may differ depending on whether a region used the Julian or Gregorian calendar at that time. This tool applies the proleptic Gregorian calendar for all years, which matches most modern systems and expectations—but if you need country-accurate historical weekdays, consult a dedicated historical calendar reference.

Troubleshooting & tips

Why is the weekday different from my record?

Check whether the other source uses a different calendar system (Julian vs Gregorian) or interprets the date with a timezone shift (some systems store timestamps at midnight UTC which can change local day). This tool treats your selection as a local calendar date, which is the usual expectation for planning and human-readable dates.

Leap-year edge cases (e.g., 1900)

The Gregorian rule: years divisible by 4 are leap years except years divisible by 100 unless they are divisible by 400. So 1900 is not a leap year, while 2000 is. This affects weekdays for dates around Feb 28–Mar 1.

Frequently Asked Questions

Is this calculator reliable for any date?

Yes for modern usage. The calculator uses standard calendar rules (proleptic Gregorian). For precise historical weekday verification in a specific country around the Gregorian adoption, consult specialist sources.

Does the selected time zone affect the weekday?

This tool treats the input as a local calendar date (no time-of-day). If you need timezone-sensitive results (e.g., an instant at 00:30 UTC that is a different local date), use the time zone converter or date/time tools on this site.

Can I share the selected date?

Yes — use the Copy and Copy Link buttons to share the weekday or a link with the date pre-filled.