What does the Birthday Calculator do?

Find your day of birth, star sign, Chinese zodiac, days alive and upcoming milestone birthdays. All calculations are performed in your browser using official UK rates and thresholds.

Is this calculator free to use?

Yes. All calculators on Calks.uk are completely free to use. No account or registration is required. All calculations run in your browser — no data is collected.

Can I use this on my phone?

Yes. All our calculators are fully responsive and work on smartphones, tablets and desktop computers. The interface adapts to your screen size automatically.

Birthday Calculator

Find your day of birth, star sign, Chinese zodiac, days alive and upcoming milestone birthdays.

Last updated: April 2026 · Source: Royal Museums Greenwich — Day of the week calculator

Date of Birth

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

Enter your date of birth and this calculator reveals the day of the week you were born, your star sign, your Chinese zodiac animal, your birthstone and how many days until your next birthday. It also shows fun facts like the number one song or major event on your birth date.

The day-of-week calculation uses Zeller's congruence, a well-known mathematical formula that works for any date in the Gregorian calendar. The Chinese zodiac follows a 12-year cycle — each year is associated with an animal sign based on the lunar new year date.

Example: Born 23 July 1995

Day of the week: Sunday
Star sign: Leo (23 Jul – 22 Aug)
Chinese zodiac: Pig (Year of the Pig, 1995)
Days until next birthday: calculated from today's date

Source: Royal Museums Greenwich — Day of the week calculator

Frequently Asked Questions

What does the Birthday Calculator do?: Find your day of birth, star sign, Chinese zodiac, days alive and upcoming milestone birthdays. All calculations are performed in your browser using official UK rates and thresholds.
Is this calculator free to use?: Yes. All calculators on Calks.uk are completely free to use. No account or registration is required. All calculations run in your browser — no data is collected.
Can I use this on my phone?: Yes. All our calculators are fully responsive and work on smartphones, tablets and desktop computers. The interface adapts to your screen size automatically.