Free birth chart calculator
Find your Sun, Moon and Rising signs and where every planet was when you were born, calculated from real astronomical positions and explained in plain English.
What a birth chart is
A birth chart (or natal chart) is a map of the sky at the moment and place you were born. It records which zodiac sign the Sun, Moon and each planet were in, which sign was rising on the eastern horizon, and how all of that falls across the twelve houses. Most people know only their Sun sign. The chart shows the full picture, which is why two people with the same Sun sign can feel so different.
What you need
- Birth date. Enough for the Sun and the slower planets.
- Birth time. Needed for your Rising sign and houses, and sometimes for the Moon. Check a birth certificate, hospital records or a baby book. Even "around 8 in the morning" is better than nothing.
- Birthplace. The nearest larger town works fine. It sets your time zone and the horizon your Rising sign is measured from.
Not sure how to make sense of it once you have it? Start with the big three, then read how to read a birth chart and the twelve houses.
How this calculator works
Many free chart tools are black boxes. Here is exactly what this one does:
- Your local birth time is converted to Universal Time using the historical time zone rules for your birthplace, including past daylight saving changes.
- The positions of the Sun, Moon and planets are calculated with Astronomy Engine, an open-source library based on modern models of planetary motion.
- Positions are measured along the ecliptic in the tropical zodiac, so 0° Aries is the spring equinox point.
- The Ascendant and Midheaven are calculated from your birthplace's latitude and longitude and the sidereal time at birth.
- Houses use the whole sign system, and a planet counts as retrograde if it appeared to move backward against the stars that day.
The written meanings are a starting point for reflection, not a prediction. Astrology isn't a science, and your chart doesn't decide who you are. Many people still find it a useful vocabulary for noticing patterns in themselves.
Birth chart FAQ
Is this birth chart calculator free?
Yes. It is free, there is no sign-up, and your birth details are not stored. The chart is calculated when you submit the form and then discarded.
How accurate are the planet positions?
Positions are calculated with the open-source Astronomy Engine library, which models the real orbits of the Sun, Moon and planets. Results typically agree with professional ephemerides to within a small fraction of a degree.
Why do I need my birth time?
The Rising sign changes roughly every two hours and the houses depend on it, so they need a birth time. The Moon also moves about 13° a day, so near a sign change the time decides which sign it was in. Planet signs for the Sun and slower planets rarely depend on the exact time.
What house system do you use?
Whole sign houses: the sign rising at your birth becomes the entire 1st house, the next sign the 2nd, and so on. It is the oldest house system and the easiest to read, and it avoids distorted houses for people born far from the equator.
Is this the tropical or sidereal zodiac?
Tropical, which is what most Western astrology uses. Signs are measured from the spring equinox point, so they line up with the seasons rather than with the constellations.
City data from GeoNames (CC BY 4.0). Planet positions by Astronomy Engine (MIT). For reflection and entertainment, not professional advice.