AstrodamusWhat is a birth chart?
A birth chart, or natal chart, is a map of the sky at the exact moment and place you were born. It shows where the Sun, the Moon and the planets sat along the zodiac, and how they were arranged around the horizon where you took your first breath.
Your sun sign is just one line on that map. The full chart also includes your Moon sign, your Rising sign, ten planets, twelve houses and the angles between them. This is why two people with the same sun sign can be so different.
What you need to make your chart
- Date of birth. This places the Sun and the slower planets.
- Time of birth. Get it as exact as you can. The Rising sign changes roughly every two hours, and the houses shift by the minute. Your birth certificate or hospital record is the best place to look.
- Place of birth. The city is enough. Astrodamus finds its coordinates and works out the time zone and daylight-saving rules that applied on that date.
Don’t know your birth time? Tick “I don’t know my birth time”. You’ll still see every planet’s sign and the aspects between them. We hide the Rising sign and houses instead of guessing them. One more catch: the Moon moves about 13° a day, so if it changed sign on your birthday, its sign depends on the time too.
How to read your birth chart
Start with your big three
Your Sun sign is your core drive, the person you’re growing into. Your Moon sign covers your emotional needs and what makes you feel safe. Your Rising sign, or Ascendant, is how you meet the world and how others first see you. Put the three together and you have a rough sketch of the whole person.
Planets: the what
Each planet stands for a part of you. Mercury is how you think and talk. Venus is how you love and what you value. Mars is how you act and compete, Jupiter is where you grow, and Saturn is where you build discipline. Uranus, Neptune and Pluto move slowly, so they say as much about whole generations as about individuals.
Signs: the how
A planet’s sign colours the way it works. Mars in Aries acts fast and directly. Mars in Libra weighs things up and looks for fairness first. The twelve signs sort into four elements (fire, earth, air, water) and three modes (cardinal, fixed, mutable). How those are balanced in your chart tells you a lot about your temperament.
Houses: the where
The twelve houses split the sky into areas of life: self, money, communication, home, creativity, health and work, relationships, shared resources, travel and belief, career, friends and the inner life. A planet’s house shows where its energy plays out. Astrodamus uses Placidus houses by default. You can switch to Whole Sign, Koch, Equal and others in the settings.
Aspects: the conversation
Aspects are the angles between planets. They show which parts of you cooperate and which pull against each other.
- Conjunction (0°): two planets merge into one strong theme.
- Sextile (60°): an easy opening you can take if you want it.
- Square (90°): friction that pushes you to act and grow.
- Trine (120°): a natural talent that comes easily.
- Opposition (180°): two sides of you that need balancing.
In the app, tap any planet, house or aspect line on the wheel to see what it means in your chart. For more detail, read Your first chart and Planets, houses and aspects.
How Astrodamus calculates your chart
Planet positions come from the Swiss Ephemeris. It’s the standard in professional astrology software and is accurate to within an arc-second. We also apply the historical time zone and daylight-saving rules for your birthplace and date. More in Time zones and daylight saving.
The calculation runs in your browser. Your birth details stay on your device unless you choose to save the chart to your account.
Free, and what comes next
Your natal chart, the wheel and the plain-English reading are free forever. You don’t need to sign up or enter a card. If you want more, Basic adds daily transits, the lunar calendar, best days and compatibility. Pro adds the professional toolkit: progressions, returns, horary, rectification and Vedic charts. See plans and pricing.
Birth chart questions
Is this birth chart calculator really free?
Yes. The chart, the wheel and the reading are free, and you can see them without an account.
Why is my sign different on another site?
Most Western astrology uses the tropical zodiac, which is tied to the seasons. Astrodamus uses it by default. Vedic astrology uses the sidereal zodiac, which is tied to the stars and currently sits about 24° earlier, so many planets land one sign back. A wrong birth time or time zone can also shift your Moon, Rising sign and houses.
Can I save or share my chart?
Yes. Make a free account to save charts and open them on any device, or share your big-three card. See Saving charts.
Is astrology a substitute for professional advice?
No. Use your birth chart for reflection and self-understanding. It doesn’t predict fixed events. For medical, legal, financial or mental-health decisions, talk to a qualified professional.