How to Get a Birth Chart (and Read the Basics)
What you need before casting a birth chart, what the wheel is actually showing you, and the four things worth looking at first.
Getting a birth chart takes about thirty seconds. Understanding what came back takes considerably longer, and most people stall at the point where a wheel full of symbols appears and nothing about it is self-explanatory.
This is the part before interpretation: what you need to supply, what the picture means, and where to look first.
What you need
Three things: date of birth, place of birth, and time of birth.
The first two are usually easy. The third is where it falls apart, and it is not a minor detail. The Ascendant — the sign rising on the eastern horizon at the moment you were born — moves through roughly one degree every four minutes, so it changes sign about every two hours. Get the time wrong by three hours and you have someone else's rising sign, someone else's houses, and quite possibly the wrong Moon.
In most countries the long-form birth certificate records the time. It is worth ordering if you do not have it. Family memory is not reliable here; "sometime in the evening" is a four-hour window and that is not good enough.
Without a time, cast the chart for noon and accept that the Sun and the outer planets are correct, the Moon is probably correct, and the Ascendant and houses are unknown. Any tool that hands you a confident rising sign with no birth time is guessing.
What the wheel is showing
The chart is a map of the sky from one place at one moment, flattened into a circle. Four things are drawn on it.
The signs are the twelve 30-degree divisions around the outside. They describe how a planet expresses.
The planets are the symbols placed around the wheel. Each one governs a function — the Moon is emotional need, Mercury is thinking and speech, Venus is attraction and value, Mars is drive.
The houses are the twelve segments dividing the wheel from the centre. They describe the area of life a planet operates in: work, relationships, home, money. Houses depend entirely on the birth time, which is why the time matters so much.
The aspects are the lines drawn across the middle, marking the angular relationships between planets. They tell you which parts of the chart are in conversation with each other.
The four things to look at first
A full chart has hundreds of readable details and looking at all of them at once is how people bounce off astrology. Start with four.
The Sun is what you already know from horoscopes, and it is the least interesting of the four because it is the only one most people have ever been told. It describes the identity you are growing into rather than your personality.
The Moon is more useful. It describes what you need, how you react before you have thought about it, and what you are like when tired or under pressure. People are often much more recognisable in their Moon than their Sun.
The Ascendant is the sign that was rising when you were born. It describes how you come across and how you approach anything new — the interface rather than the machine.
The house each planet sits in. This is the step most beginners skip, and it changes everything. A Leo Sun in the sixth house is not a performer; it is someone whose sense of self is built out of doing their work properly. The sign describes the style, the house describes where it happens, and reading the sign without the house gives you horoscope-level generality.
What free tools give you and where they stop
A free calculator will give you an accurate chart. That is genuinely most of the value, and you do not need to pay for planetary positions.
Where free tools generally stop is everything after the first look: saving the chart, keeping notes on it, comparing it to someone else's, tracking what is currently transiting it, or getting interpretation that synthesises the chart rather than listing placements one at a time. Whether that matters depends entirely on whether you are looking once out of curiosity or coming back to this repeatedly.
What to be sceptical of
Any interpretation that reads as though it could be about anyone is telling you about the placement in general rather than about this chart. The useful version references the specific configuration and could not be pasted into someone else's reading unchanged.
Be sceptical of confident predictions with dates attached to natal placements. A natal placement is fixed for life and cannot date anything. Timing comes from things that move — transits, progressions, profections — and a reading that dates an event from a birth placement alone is making it up.
And be sceptical of compatibility scores. A single percentage has to collapse dozens of separate contacts into one number, and the weighting doing the collapsing is arbitrary.
Where to go next
You can cast a free chart with no account, and there is a step-by-step guide to reading one that goes considerably deeper than this. If a term on your chart is unfamiliar, the glossary defines them in plain English.
Frequently asked questions
What information do I need for a birth chart?
Date, place and time of birth. The time is the one that matters most — the Ascendant moves about a degree every four minutes and changes sign roughly every two hours.
Where can I find my birth time?
In most countries it is recorded on the long-form birth certificate, which is worth ordering. Family recollection is not reliable enough, since "sometime in the evening" is a four-hour window.
What should I look at first on my birth chart?
The Sun, Moon and Ascendant, then the house each planet occupies. The house is the step beginners skip and it changes the meaning more than the sign does.
What is the difference between a sign and a house?
The sign describes how a planet expresses; the house describes which area of life it operates in. A Leo Sun in the sixth house is not a performer, it is someone whose identity is built on doing their work properly.