What are Sun, Moon and rising signs?
A birth chart, also called a natal chart, maps planetary positions for your birth date, local time and birthplace. This free calculator uses the Western tropical zodiac: twelve equal 30-degree signs measured from the March equinox. Your Sun, Moon and rising signs are often called the “Big Three.” They describe three different symbolic lenses rather than a complete definition of who you are.
Sun · your direction
In astrology, the Sun is associated with identity, vitality and the qualities you grow into. A Sun sign calculator finds where the Sun was along the zodiac at birth. Use it as a question about what feels meaningful, rather than a fixed personality label.
Moon · your inner rhythm
The Moon is associated with emotional habits, comfort and instinctive responses. It moves quickly enough that a birth date alone can be insufficient near a sign change. Your Moon sign may help you reflect on what restores you and how you respond when you need support.
Rising · your first step
The rising sign, or Ascendant, is the zodiac sign crossing the eastern horizon at birth. It depends on your time and geographic location. Astrologers use it to discuss how you enter situations and meet the world. It cannot be recovered reliably from your date alone.
How to use the birth chart calculator
- Enter your birth date and the local clock time recorded at your birthplace. Use a birth certificate or other reliable record when available.
- Search for your city and select the correct country and region. The calculator fills the coordinates and time zone. If your town is missing, enter its coordinates and IANA zone under location details.
- Choose “I don’t know” if your birth time is unavailable. We check the whole local day, show only signs that remain clear, and leave the rising sign blank.
- Calculate your chart, then review the Sun, Moon and rising cards and the ten-planet table. The result stays in this tab; refreshing or leaving the page clears it.
How this calculator works
Planetary positions come from Astronomy Engine, the open-source astronomy library also used by Astrea. We calculate geocentric ecliptic longitudes of date, including the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. The Ascendant is the eastern intersection of the horizon and ecliptic. This tool reports signs and degrees; it does not generate houses, aspect readings or an AI interpretation.
City coordinates and time zones come from a static GeoNames city snapshot, distributed under CC BY 4.0. Search covers 34,006 cities by their listed names. Larger cities appear first; country and administrative region help distinguish namesakes. For a precise birthplace, you can override both coordinates and the time zone.
Local times are converted using IANA time zones and your browser’s historical time-zone data. A clock time skipped during a daylight saving change is rejected. If a time happened twice when clocks moved back, the calculator asks you to select the recorded occurrence. For an unknown time, hourly samples and a conservative boundary margin help avoid claiming a sign close to an ingress. Precise degrees and a personalized wheel are omitted in that mode.
Birth chart calculator questions
Can I calculate a birth chart without a birth time?
Yes, with limits. Select “I don’t know” to check the entire local date. A planet whose sign changes that day, or sits too near a boundary, is marked uncertain. Rising is unavailable. No noon chart is presented as your exact birth chart.
Why is my rising sign missing?
It needs a known birth time and location. We also omit the Ascendant at latitudes of 66 degrees north or south and beyond, following Astrea’s conservative polar policy. The Sun, Moon and other planetary positions can still be calculated there.
Why is my sign different from a date-range horoscope?
Calendar sign dates are approximate. The Sun enters each sign at a particular instant, which changes slightly each year. Birth time and time zone can therefore matter near a boundary. Sidereal calculators also use a different zodiac reference and can produce different signs.
Are my birth details saved or sent to an AI?
No. This tool computes in your browser and does not store your inputs in cookies, browser storage or a database. The website uses page and CTA analytics; birth fields and chart results are excluded from those events. The Astrea app has its own data practices, described in its privacy policy.
Does a birth chart predict what will happen to me?
This page offers an astrology-based reflection tool. Astronomical positions are calculated; their astrological meanings are interpretive and are not established scientific predictions. You can explore what resonates without treating a placement as a verdict or an instruction.
What can I do next in Astrea?
Explore your personal chart, read a daily reflection, ask a question grounded in your chart and keep a journal. The Astrea product page explains the current features, free and Pro limits, supported languages and availability.
Created and reviewed by SECOND WIND LIMITED · . We publish Astrea and this calculator. Third-party notices.