Day of the Week Calculator
Pick any date to find out which day of the week it falls on, in your own language.
Last updated: June 20, 2026 · Reviewed by TG we-Calculate Editorial TeamDate
That date is a Thursday — January 1, 2026
- 1
Days elapsed since Jan 1
(date UTC − Jan 1 UTC) ÷ 86,400,000 = 0UTC timestamps avoid daylight-saving edge cases. Jan 1 itself gives 0 days elapsed. - 2
Day of year
0 + 1 = 1Day 1 = January 1, so we add 1 to the zero-based elapsed count.
How do you find what day of the week a date falls on?
To find the day of the week for any date, count forward from a known reference weekday using the Gregorian calendar, accounting for leap years. This calculator does it instantly: enter a date and it returns the weekday name in your language, plus the day of year and ISO week number.
Formula
How this is calculated
The single input is a calendar date (year, month and day). The date is parsed at midnight local time and the weekday is read straight from the proleptic Gregorian calendar — the civil calendar used worldwide — so Monday through Sunday come out the same for everyone, no counting required. The weekday name is then formatted in your locale, which is why French visitors see "lundi" and German visitors see "Montag" for the same underlying day.
Three extra figures are derived from the same date. The day of year counts whole days from January 1 (= day 1) up to the chosen date, giving a value from 1 to 365, or 366 in a leap year. The ISO 8601 week number is computed by shifting to the Thursday of that week (weeks start on Monday, and week 1 is the one containing the year's first Thursday), which can place early-January or late-December dates in a neighbouring year's numbering. The leap-year flag applies the rule: divisible by 4, except centuries unless divisible by 400.
Calculations run in UTC internally to avoid daylight-saving shifts. Dates before the 1582 Gregorian reform use the proleptic extension, so weekdays may differ from old Julian-calendar records.
Examples
| Input | Result |
|---|---|
| 2026-01-01 | Thursday (day 1 of 2026) |
| 2000-01-01 | Saturday (leap year) |
| 2026-12-25 | Friday (day 359 of 2026) |
About this calculator
The day of the week calculator tells you which weekday — Monday through Sunday — a given date falls on. Enter any past or future date and it returns the weekday name in your locale, along with the day of the year (1 to 366), the ISO 8601 week number and whether the year is a leap year.
Use it to find the weekday you were born, check which day a holiday or anniversary lands on, or plan around a future deadline. The weekday is derived from the proleptic Gregorian calendar, the civil calendar used worldwide today, so results are consistent for any modern date.
Frequently asked questions
A year is a leap year if it is divisible by 4, except for century years, which must be divisible by 400. So 2000 was a leap year but 1900 was not. Leap years have 366 days instead of 365.
The weekday name is formatted with your browser locale, so French visitors see "lundi", German visitors see "Montag", and so on. The underlying day of the week is the same everywhere.
Yes, it uses the proleptic Gregorian calendar, extending today's civil calendar backwards. For historical dates recorded under the older Julian calendar, the weekday in local records may differ.
Also known as
Sources & references
TG we-Calculate Editorial Team. (2026). Day of the Week Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/day-of-week-calculator
TG we-Calculate Editorial Team. "Day of the Week Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/day-of-week-calculator.
TG we-Calculate Editorial Team, "Day of the Week Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/day-of-week-calculator
@misc{wecalculate_day_of_week_calculator, title = {Day of the Week Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/day-of-week-calculator}}, year = {2026}, note = {TG we-Calculate} }
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