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Free calculator · Astrology

Sun Sign Calculator

Your Sun sign, your star sign, is the sign of the zodiac the Sun stood in when you were born. The Sun changes sign every month, on a different day from year to year; if you were born on such a day, time and place decide. The calculator works it out the way the UmbraLux app does and names the minute of the change.

Date of birth

As exact as you can, ideally from your birth certificate.

Your place is missing? Take the nearest town; a few kilometres hardly change the result.

The calculation runs in your browser. Your birth data is neither sent nor stored; only this device remembers your last entry. · Place data: GeoNames (CC BY 4.0)

How the Sun sign is calculated

The calculator runs the same calculation as the UmbraLux app, in three steps:

  1. 1

    Turn the clock time into Universal Time

    Your birth time is the clock time at your birthplace. With the time zone that applied there on that day (the IANA time zone database knows summer times and older rules), it becomes Universal Time (UTC). Without a time, the calculator takes your whole birthday at your birthplace.

  2. 2

    Calculate the position of the Sun

    For that moment the ephemeris gives the apparent geocentric longitude of the Sun on the ecliptic of date: where the Sun stood in the zodiac, seen from the Earth.

  3. 3

    Read the sign

    The longitude divided by 30° gives the sign: 0° to 30° is Aries, 30° to 60° Taurus and so on (tropical zodiac). The remainder is the degree within the sign.

Example: 15 May 1990, 14:30, Berlin

On 15 May 1990 summer time applied in Berlin (UTC+2), so 14:30 was 12:30 Universal Time. At that moment the Sun stood at 24°24′ Taurus.

The Sun had entered Taurus on 20 April 1990 and left it on 21 May 1990: anyone born in that time has the Sun in Taurus.

What the Sun sign means in astrology

Astrology reads the Sun as your core: how you show yourself, what gives you strength, where you want to grow. The Moon and the Ascendant complete it; together they are often called the big three of a chart.

When the Sun changes sign

From 1940 to 2030 the Sun entered the signs on these days (Universal Time): Aquarius: 19 to 21 January · Pisces: 18 to 19 February · Aries: 20 to 21 March · Taurus: 19 to 20 April · Gemini: 20 to 21 May · Cancer: 20 to 22 June · Leo: 22 to 23 July · Virgo: 22 to 24 August · Libra: 22 to 23 September · Scorpio: 22 to 24 October · Sagittarius: 21 to 23 November · Capricorn: 21 to 22 December.

If you were born on one of these days, the time decides: depending on the year, the Sun changed sign on another of them and at another hour.

In the library

Questions about the Sun sign

Why is my Sun sign not certain although I know my birth date?

Because the Sun does not change sign on the same day every year but a day earlier or later, depending on the year, and at a certain time of that day. Born on such a day, you find your sign with your time and place; without a time the calculator names the minute of the change.

What is a cusp?

Some astrologers call a birth close to the border of two signs a cusp birth. By the calculation the Sun always stands in exactly one sign; the calculator shows at which degree and arcminute.

How accurate is the calculator?

In 5,000 samples from 1900 to 2100 the Sun lay one arcsecond on average and six at most from a calculation on the Swiss Ephemeris; the Sun covers six arcseconds in about two and a half minutes.

Why does another calculator show a different sign?

Fixed table dates such as "Aries: 21 March to 19 April" do not hold every year: from 1940 to 2030 the Sun entered Aries on 20 or on 21 March, depending on the year. Vedic astrology also uses the sidereal zodiac, whose signs lie about 24 degrees further back at present.

Is my data stored?

No. The calculation runs in your browser; your date, time and place are neither sent nor stored. Only your device remembers your last entry, and you can delete it below the form.

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