Big Three calculator: your Sun, Moon and rising sign

Your "Big Three" in astrology are your Sun sign, Moon sign and rising sign (Ascendant). The Sun is traditionally read as your core identity, the Moon as your emotional needs and the rising sign as the way you meet the world. The Sun needs only your birth date; the Moon sometimes and the rising sign always need your birth time and place.

Sun sign

Moon sign

Rising sign

Hidden card – fill in your birth data to reveal it

Updated 8 November 2026
How we calculate it
Computed on your device

Enter your birth details once and get all three signs as cards you can save or share, each with a short description and a link to the full birth chart.

Without a birth time you still get your Sun sign (and usually your Moon sign). We mark the rising sign as unknown and show the possible options by time of day.

How we calculate it

Planet positions come from Astronomy Engine, an open-source astronomy library (MIT license) whose author documents an accuracy of about ±1 arcminute. We use apparent geocentric positions on the true ecliptic of date (IAU 2006 precession and IAU 2000B nutation, with light-time and aberration) – the same definition most astrology software uses.

Your local birth time is converted to Universal Time with the historical rules of the IANA time zone database, including past daylight-saving changes and war-time clocks. City coordinates and time zones come from GeoNames. If a time was skipped or repeated because the clocks changed, we tell you instead of guessing silently. One honest limit: for births before about 1970 the database is not guaranteed to be complete, and a small town may have kept a different local time than the reference city of its zone. We always show the UTC offset we applied, so you can compare it with what you know (for example a time on a birth certificate).

We test the engine against NASA/JPL Horizons (DE441) for reference birth data: planets agree within 1 arcminute and the Moon within 2; the Ascendant and Midheaven, computed from Horizons sidereal time, agree within 3 arcminutes.

Everything runs in your browser. Your birth data is not sent to a server and nothing is stored.

Which of the three needs what

Sun sign: date of birth (plus time only if you were born on the day the Sun changed sign). Moon sign: date, and time on days when the Moon changed sign. Rising sign: exact time and place – it changes on average every two hours.

Questions

What are my big 3 signs?

Your Sun, Moon and rising sign. Enter your birth date, time and place above to see all three.

Can I find my Big Three without a birth time?

Partly. You get the Sun sign and, on most days, the Moon sign. The rising sign needs a birth time; without it we show the possible rising signs and their time windows.

Which of the Big Three is most important?

Astrologers differ. Many start with the Sun, but the Moon and Ascendant are often felt just as strongly. They are best read together, as layers of one picture.

What is the "Big Six" in astrology?

Some astrologers extend the Big Three with Mercury, Venus and Mars – the personal planets that describe thinking, affection and drive. You can see them in the full birth chart.

Is the Big Three the same as a birth chart?

No, it is a summary of three key points. A full birth chart also includes the other planets, houses and aspects.

Sources

Astrology, numerology and the Chinese zodiac are offered for entertainment and self-reflection. They are not scientifically validated and are not a substitute for professional advice (medical, psychological, legal or financial). Astronomical positions are calculated precisely; interpretations are traditional symbolism, not predictions.