Zodiac sign calculator: sun, moon and rising
This zodiac sign calculator goes further than a date chart: from your date, time and place of birth it works out where the Sun and Moon were and which sign was rising. Someone born on May 15, 1990 at 2:30 p.m. in New York is a Taurus with Virgo rising.
Source: NOAA Global Monitoring Laboratory: Solar Calculation Details (formulas from J. Meeus, Astronomical Algorithms). Updated: .
How it is calculated
How your zodiac sign is calculated
Your sun sign is the 30° section of the ecliptic the Sun was in when you were born. Western (tropical) astrology counts from the March equinox: 0–30° Aries, 30–60° Taurus and so on. Because the calendar year does not match the Sun’s path exactly, the sign boundaries shift by up to a day from year to year – so the calculator shows the exact ingress times for your birth year instead of a fixed chart.
The Sun’s position uses Jean Meeus’s formulas from “Astronomical Algorithms”, the same ones behind the NOAA solar calculator; they place the equinoxes to within about ten minutes. The Moon follows the ELP-2000/82 lunar theory. Your rising sign (ascendant) is the point of the ecliptic rising on the eastern horizon at the moment of birth; it depends on time and place and changes sign roughly every two hours. Local time is converted to Universal Time with the IANA time zone database, including historical daylight saving time.
Approximate zodiac dates
| Sign | Approximate dates | Element |
|---|---|---|
| ♈ Aries | Mar 21 – Apr 20 | Fire |
| ♉ Taurus | Apr 21 – May 20 | Earth |
| ♊ Gemini | May 21 – Jun 21 | Air |
| ♋ Cancer | Jun 22 – Jul 22 | Water |
| ♌ Leo | Jul 23 – Aug 23 | Fire |
| ♍ Virgo | Aug 24 – Sep 23 | Earth |
| ♎ Libra | Sep 24 – Oct 23 | Air |
| ♏ Scorpio | Oct 24 – Nov 22 | Water |
| ♐ Sagittarius | Nov 23 – Dec 21 | Fire |
| ♑ Capricorn | Dec 22 – Jan 20 | Earth |
| ♒ Aquarius | Jan 21 – Feb 19 | Air |
| ♓ Pisces | Feb 20 – Mar 20 | Water |
What the calculator does not do
It computes positions, not interpretations; there is no scientific evidence for astrological claims about character or fate. The signs also no longer line up with the constellations of the same name: precession of Earth’s axis has shifted the equinox by almost a whole sign since antiquity. For the Chinese zodiac animal, see the Chinese calendar converter; for the moon phase on your birthday, the moon phase calendar.
Frequently asked questions
What is my zodiac sign?
Enter your date of birth above. If your birthday falls on a cusp (around the 19th to 23rd of the month), the time of birth decides – the calculator shows when the Sun changed sign that day.
How do I find my rising sign?
You need your date, time and place of birth. The ascendant changes sign about every two hours, so even ten minutes can matter near a boundary. Your birth certificate usually records the time.
Can I calculate my rising sign without a birth time?
No. Without the time, any of the twelve signs is possible. The sun sign and usually the moon sign can still be determined.
What is a moon sign?
The sign the Moon was in when you were born. The Moon changes sign about every two and a half days; without a time, the calculator shows whether and when it changed on your birthday.
Why do zodiac dates change from year to year?
A solar year lasts about 365.24 days while the calendar year has 365 or 366, so the Sun’s entry into each sign shifts by some hours each year and jumps back in leap years.
Sources and legal basis
- NOAA Global Monitoring Laboratory: Solar Calculation Details (formulas from J. Meeus, Astronomical Algorithms)
- U.S. Naval Observatory: Earth’s Seasons – equinox and solstice times (used as check)
- Wikipedia: Ascendant – formula from local sidereal time, obliquity and latitude
- Wikipedia: Astrological sign – tropical zodiac, precession
- IANA Time Zone Database (historical daylight saving time)
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