Live civil weekday for any Gregorian date - ISO week, day-of-year, and an anniversary strip so recurring month-days do not surprise you next year.
Calendar name only. Not a business-day engine, holiday calendar, or historical Julian converter.
By Ahmet C. Toplutaş·Site owner & editor · Time & calendar tools
Last updated May 21, 2026 · Reviewed May 21, 2026 · Planning estimates only - not tax, medical, or investment advice
01
Most people open a day-of-week tool with a simple ask: what day was (or will) this date? The honest answer is a civil Gregorian weekday — Sunday through Saturday on the calendar you almost certainly use for personal life.
That is not the same as “when does the office count this as due?” Business calendars skip weekends and holidays. A contract “due Friday” may mean Friday end of business in one timezone; a court filing “due the 15th” may roll to Monday when the 15th is Saturday. Confusing civil weekday with business deadline is how Friday filings become Monday surprises.
This page stays on the civil name; workday tools handle office math (add N business days, skip holidays). If your question is “what weekday is July 4, 2027?” you are in the right place. If it is “three business days after July 4,” start elsewhere.
Unique job of this page: weekday identity + how that month-day drifts across years — not another cost ladder or stringer layout.
02
Birthdays, lease starts, and “every July 1” rituals feel fixed on the calendar. Weekdays are not. A birthday on Saturday shifts party planning; a rent due date on Sunday may matter for bank processing even when the lease says “the 1st.”
Most years the same month-day advances one weekday (365 ≡ 1 mod 7). After a leap day sits between two anniversaries, it can advance two — so March 1 after a leap year often jumps two weekdays forward relative to the prior year’s March 1. The panel’s anniversary strip lists nearby years for the month-day you picked so you can plan without guessing from last year.
February 29 only exists in leap years — the strip marks gaps instead of inventing a fake date. For “Feb 29 birthdays,” leap years are the only valid anchors; other years require a policy (Feb 28 vs Mar 1) this tool does not choose for you.
03
Modern browsers and this panel use Gregorian rules. Extending those rules backward (proleptic Gregorian) is convenient for software and wrong for some historical documents written under Julian or local reform calendars.
Catholic Europe adopted in 1582 (Thursday Oct 4 was followed by Friday Oct 15). Britain and American colonies shifted in 1752; Greece in 1923; Turkey in 1926. A letter dated “Wed 2 Sep 1752” in England is Julian; the weekday you get from a modern Gregorian calculator may not match contemporary diaries.
If you are doing genealogy or archival work before reform, treat the weekday as a software convention until you confirm the calendar system in the source. For dates after 1900 in most countries, proleptic Gregorian is usually fine for personal planning.
04
People often say “week” meaning Sunday–Saturday on a wall calendar. ISO 8601 weeks start Monday, and week 1 is the week containing the year’s first Thursday. That definition can assign early January days to week 52/53 of the prior year, or late December days to week 1 of the next.
The panel shows ISO week next to the civil weekday so spreadsheet and ERP “week 12” labels do not silently disagree with a Sunday-start planner. If you export “W12” from Excel, confirm whether the workbook uses ISO or a locale default — this page shows ISO explicitly.
05
Example A — today. Tap Today for the local civil date.
Sanity check: device clock and panel should agree on weekday, ISO week, and day-of-year. If they diverge, you may be in a timezone edge around midnight — this tool uses local calendar date, not UTC instant.
Example B — first of next month. Tap 1st next month for billing/lease anchors.
Suppose the 1st lands on Wednesday. Scan the anniversary strip: if next year’s same month-day is Thursday, your “every 1st” direct deposit or notice window shifts one civil day — still the 1st, different weekday. Plan bank cutoffs separately from civil naming.
Example C — leap-span drift. Pick March 15 in a leap year and compare the strip to a non-leap span.
Years containing Feb 29 often show a +2 weekday step for dates after February versus a +1 step in common years. You do not need to memorize the rule — the strip makes the extra shift visible for party planning and “same date every year” assumptions.
06
07
08
09
No. The panel shows the civil Gregorian weekday (Sunday–Saturday). Business deadlines also skip weekends and local holidays. Use a workday or business-day tool when the question is “when is this due at the office,” not “what day of the week is printed on the calendar.”
A fixed month and day walks forward one weekday most years, and two weekdays after a February 29 leap day that falls between anniversaries. The strip exists so birthday and lease renewals are planned on the correct weekday - not guessed from last year.
This tool uses the proleptic Gregorian calendar (the modern rules extended backward). Historians may need the Julian calendar or a local reform date. For genealogy or legal history before calendar reform, verify with a specialist source.
ISO 8601 weeks start on Monday and week 1 is the week with the year’s first Thursday. The panel shows that week number next to the civil weekday so scheduling systems that speak ISO and people who speak “Sunday week” can stay aligned.
For a pure calendar date (YYYY-MM-DD) the weekday is defined without a clock time. Instant-based timestamps near midnight can land on different civil dates in different zones - enter the local calendar date you care about, not a UTC instant.
Day-of-week finder answers which named weekday a date falls on (and how that month-day repeats across years). A day counter answers how many days lie between two dates. Use both when you need both the name and the span.
LIVE WEEKDAY
Anniversary years ↓Quick anchors
Gregorian civil date (local). Not a timezone instant.
Updates as you change the date. Weekday ≠ business deadline day.
Day of week
Sunday
Sunday, August 16, 2026 · ISO week 33 · day 228 of 2026
ANNIVERSARY STRIP (same month-day · nearby years)
Tap a year to jump. Leap-day gaps show when Feb 29 does not exist.
Copy the link to save or share your results.