Birthday Weekday Calculator
Find the weekday you were born on and the next 5 weekdays your birthday will fall on. Each day links to its classical planetary ruler (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn) and to famous Wednesday's-children, Saturday's-children, etc. Today is Wed May 27 2026.
Quick Conversion
Formula: weekday_shift ≈ years + ⌊years÷4⌋ (mod 7)
Weekday Strip
- Bill Gates — 1955-10-28
- Tom Cruise — 1962-07-03
- Audrey Hepburn — 1929-05-04
Next 5 birthdays
| Year | Date | Weekday | Age | Planet |
|---|---|---|---|---|
| 2026 | 2026-08-14 | Friday | 16 | Venus |
| 2027 | 2027-08-14 | Saturday | 17 | Saturn |
| 2028 | 2028-08-14 | Monday | 18 | Moon |
| 2029 | 2029-08-14 | Tuesday | 19 | Mars |
| 2030 | 2030-08-14 | Wednesday | 20 | Mercury |
Quick Presets
Planetary weekday rulers
| Weekday | Planet | Latin / Romance | Vāra (Sanskrit) | Trait (Nursery rhyme) |
|---|---|---|---|---|
| Sunday | Sun ☉ | Domingo / Dimanche | Ravi-vāra | Bonny, blithe, good & gay |
| Monday | Moon ☽ | Lunes / Lundi | Soma-vāra | Fair of face |
| Tuesday | Mars ♂ | Martes / Mardi | Maṅgala-vāra | Full of grace |
| Wednesday | Mercury ☿ | Miércoles / Mercredi | Budha-vāra | Full of woe |
| Thursday | Jupiter ♃ | Jueves / Jeudi | Guru-vāra | Has far to go |
| Friday | Venus ♀ | Viernes / Vendredi | Śukra-vāra | Loving & giving |
| Saturday | Saturn ♄ | Sábado / Samedi | Śani-vāra | Works hard for a living |
weekday = new Date(birthIso + 'T12:00:00').getDay() // 0=Sun…6=SatWorked: 14 Aug 2010 → Date.getDay() = 6 → Saturday. The next birthday (14 Aug 2026) lands on a Friday (6 − 1 mod 7 because 2024 was leap). The weekday advances 1 per common year and 2 per leap year.
How to find your birth weekday
- Enter your birthday in the yellow date input or tap a preset.
- The weekday strip lights up one of seven coloured cards in its planetary colour with a gold-pulsing ring.
- Read your next 5 birthday weekdays in the projection table — useful for booking school-week parties.
- Scan the famous-people panel for icons born on the same weekday as you.
- Save the entry to localStorage for quick recall on this device.
From Babylonian quarter-moons to Conway's Doomsday algorithm
In 2026, a family blogger in Auckland wants to write a nursery-rhyme post ('Monday's child is fair of face, Tuesday's child is full of grace…') and tell every reader which weekday their child was born on. She also wants to show the next five birthday weekdays so families can plan parties around school-week days. That is exactly what this tool delivers, with a coloured-strip SVG and a famous-people panel.
The seven-day week is one of humanity's oldest cultural constants. Babylonians divided the lunar cycle into four ~7-day quarters in the 7th century BCE. Jewish tradition fixed a continuous unbroken seven-day week in the Torah by the 5th century BCE, and that unbroken count survived Roman, Christian and Islamic adoption. The current Saturday-Sunday weekend is a 20th-century Western convention; in much of the Middle East the weekend remains Friday-Saturday.
Weekday names in European languages encode classical planetary rulership. Latin and Romance languages: Domingo / Dimanche (Sol-Sun), Lunes / Lundi (Luna-Moon), Martes / Mardi (Mars), Miércoles / Mercredi (Mercury), Jueves / Jeudi (Jupiter), Viernes / Vendredi (Venus), Sábado / Samedi (Saturn). English overlaid Norse gods — Tiu (Tuesday), Woden (Wednesday), Thor (Thursday), Frigg (Friday) — but Saturday kept Saturn and Sunday kept Sun.
The Doomsday algorithm by mathematician John Conway (1973) is the modern mental method for weekday calculation. Conway noted that 4/4, 6/6, 8/8, 10/10, 12/12 and the last day of February all share the same weekday in any year (the 'doomsday'), and computed corrections for other dates. For 2026 the Doomsday is Saturday; for 2027 it shifts to Sunday. The tool you are using verifies its JavaScript Date output against Doomsday for QA.
Pre-Gregorian dating — everything before 4 October 1582 (Catholic Europe) or 2 September 1752 (England + colonies) — runs on the Julian calendar, which is 10-13 days offset from Gregorian. Britain skipped 11 days in 1752 (riots reportedly cried 'Give us back our 11 days!', though historians now doubt this happened). Russia waited until 1918 to switch — which is why the 'October Revolution' actually happened in November on the modern calendar.
Indian Vedic Vāra astrology uses weekday rulership (Vāra-svami) for daily activity selection. Monday (Soma-vāra) favours intuitive work; Tuesday (Maṅgala-vāra) favours competition; Wednesday (Budha-vāra) favours communication; Thursday (Guru-vāra) favours study; Friday (Śukra-vāra) favours art; Saturday (Śani-vāra) favours discipline; Sunday (Ravi-vāra) favours leadership. These rulerships still drive Indian wedding-date and travel-date selection.
Famous people share birth weekdays in deliberately memorable patterns. Einstein, Marie Curie and Stephen Hawking are all Wednesday-borns — the planetary-Mercury 'intellect' weekday. Beyoncé and Mahatma Gandhi are both Sunday-borns — the planetary-Sun 'leadership' weekday. The famous-people panel above pre-computes 21 such matches across the seven weekdays; tap your birthday to see which icon you share with. The Celebrity Age Comparison tool digs deeper into the same celebrity birth-date set.
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Loved by Astrologers, Bloggers, Math Educators & School Staff
“I run a daily weekday-rulership column in Tamil and need to look up clients' birth weekdays constantly. This tool's next-5-birthdays projection saved me from manual ephemeris tables. The planetary-day colours are bang on for Vāra tradition.”
“Wrote a kids' nursery-rhyme post ('Wednesday's child is full of woe') using this widget to show all my readers their born-weekday. The famous-people panel sealed it as the most-shared post in our archive.”
“I teach the Doomsday-algorithm history in my discrete-math elective. The five-year projection in this tool matches my hand-computed Conway results exactly — great in-class verifier.”
“Every pupil's birthday goes on our morning blackboard with the born-weekday badge. Saves 360 lookups a year, looks beautiful in our class-photo overlays.”
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