Birth chart calculator
Your sun sign is one line out of a dozen. This gives you the whole chart — Moon, rising, all nine planets, the houses they fall in, and which of them were retrograde.
What each placement is for
SunIdentity
The self you build on purpose and recognise as you. This is the sign almost everyone already knows, and it is one placement out of a dozen.
MoonEmotional default
How you react before you have decided how to react, what settles you, and what you need to feel safe. Usually the placement people find most accurate.
Ascendant (rising sign)The arrival
How you come across before anyone knows you. It depends on your exact birth time, which is why a chart without one is missing its frame.
MercuryThinking and speech
How you take information in and how you hand it back. It never strays far from the Sun, so it is either your Sun sign or one adjacent to it.
VenusWhat you value
Taste, affection, and what you find worth having. In relationship readings it carries more weight than the Sun does.
MarsDrive and anger
How you pursue what you want and what you do when blocked. Two people with the same Sun and different Mars fight nothing alike.
JupiterGrowth and excess
Where you expand, take chances and overreach. It spends about a year in each sign, so it is shared with everyone born around the same time.
SaturnLimits and discipline
Where the work is, and where you are slowest to feel adequate. Its return at about twenty-nine is the transit people notice most.
UranusDisruption
Where you break the pattern. Seven years to a sign, so it describes a generation more than a person.
NeptuneImagination and blur
Where the edges go soft — inspiration, and also where you are easiest to fool. Around fourteen years to a sign.
PlutoPower and change
Where things are stripped down and rebuilt. It takes twelve to thirty years to cross a sign, so it marks an era.
Why two people born the same day are not alike
The Sun takes a month to cross a sign, so everyone born in the same few weeks shares it. The Moon crosses one in two and a half days, and the ascendant in about two hours. That is where the differences live: same birthday, different hour, and the chart reads as a different person.
The slow planets work the other way. Uranus spends seven years in a sign, Neptune about fourteen, Pluto twelve to thirty — so those placements describe a generation rather than an individual, and are read for the era someone was born into rather than their temperament.
Frequently asked questions
What is a birth chart?
A birth chart, or natal chart, is a map of where the Sun, Moon and planets were at the moment and place you were born. Your sun sign is one line of it. The chart adds the Moon, the ascendant, the seven other bodies, and the houses those bodies fall in — which is why two people born on the same day can read nothing alike.
Do I need my exact birth time?
For the planets, no. For the ascendant and the houses, yes. The whole zodiac passes the eastern horizon once a day, so the rising sign changes roughly every two hours and twenty minutes of error can move it into the next sign. Without a time this calculator gives you the planetary signs and declines to invent a rising sign.
What does retrograde mean in a birth chart?
That the planet appeared to move backwards against the stars when you were born. The motion is apparent rather than real — it happens when the Earth overtakes an outer planet on the inside — but it is a standard part of a reading, so this chart marks it. Roughly one person in five has three or more retrograde planets.
Which house system does this use?
Whole sign. The sign rising on the eastern horizon is the entire first house, the next sign the second, and so on. It is the oldest system in use, it is what Hellenistic astrology used, and it is the one that stays honest when a birth time is approximate rather than exact to the minute.
How accurate are the positions?
The planetary positions are computed from standard orbital elements with the major perturbation terms, accurate to a few arcminutes — far finer than the one-degree resolution shown. The Moon uses a separate, more precise series because it moves fast enough to matter. In practice the largest source of error in any chart is the birth time and time zone entered, not the astronomy.
Is my birth data stored?
No. Everything is calculated in your browser. Your birth date, time and city are never sent to our servers, logged, or attached to an account.
Keep going
Moon sign calculator · Rising sign calculator · All twelve sign profiles · Chinese zodiac