Birth chart calculator
A birth chart is the sky as it stood from the place you were born at the moment you were born: which sign each planet was in, how far above or below the horizon, and the angles they made to one another. It is not a forecast and it does not change. Everything else in astrology — every forecast, every comparison, every technique on this site — is read against it.
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Birth Chart
Three things go into it and all three matter. The DATE fixes where the planets were, and for the slow ones that is nearly the whole story. The TIME fixes the houses and the angles, which decide which part of life each planet belongs to; the Ascendant moves a degree every four minutes, so an hour of error moves it fifteen degrees and can change the rising sign entirely. The PLACE fixes the horizon the whole frame is built from.
What comes back here is the chart wheel, every planet with its sign, degree and house, and the aspects between them — with the closest first, because an aspect two degrees from exact says more than one nine degrees away. The positions are calculated with the Swiss Ephemeris, which is the same engine professional astrologers use, and the houses with the system you choose.
The report also sorts the chart by weight, which is the part most calculators leave out. A chart is not a list of twelve equal facts: a planet on an angle, or one that several others aspect, or the ruler of the rising sign, carries more than a planet sitting quietly in the middle of a house. Reading the ordering is the fastest way to learn what a chart is mainly about.
If you do not know your birth time you can still cast the chart, and it is still worth having. The planets will be right to within a fraction of a degree, except the Moon, which moves about half a degree an hour, so its sign is safe unless it changed sign that day. What you will not get is the Ascendant, the Midheaven or the houses — read the signs and the aspects and treat the houses as missing rather than as approximate.
A chart is a description, not a verdict. Nothing in it says what will happen or what you must be; a hard aspect names something that will keep asking for attention rather than a sentence passed on you, and an easy one names something that comes cheaply enough to be wasted. What it is genuinely good for is recognising a pattern you already half knew about, and being specific about it.
Once the chart is cast, everything else here builds on it: the forecast reads what is passing over it now, the returns cast a fresh chart at the moment a planet comes home, the progressions move it forward, and the relationship reports set it beside somebody else's. Start here, then go where the question takes you.
Questions people ask
What is a birth chart?
A map of the sky from your birthplace at the moment you were born: the planets by sign and degree, the houses drawn from the local horizon, and the aspects between everything. It does not change and it is what every other technique is read against.
Do I need my exact birth time?
For the planets, no — a date is usually enough. For the Ascendant, the Midheaven and the houses, yes. The Ascendant moves a degree every four minutes, so an hour of error moves it fifteen degrees and can change your rising sign completely.
What can I read without a birth time?
Every planet's sign and degree, and every aspect between them, which is most of the chart. Only the Moon is fast enough for the hour to matter, and then only if it changed sign that day. Leave the houses out rather than guessing them.
Which house system does this use?
Whichever you set in your profile — Placidus by default, as most Western astrologers use. The planets are identical in every system; only the house each falls into can differ, and near a cusp it often does.
What does it mean that the chart is "sorted by importance"?
That the report weighs the placements rather than listing them flat. A planet on an angle, one that several others aspect, or the ruler of your rising sign carries more weight than one sitting quietly mid-house — and reading that order is the quickest way to see what a chart is mostly about.
Is my birth chart good or bad?
Neither, and any calculator that tells you otherwise is selling something. A hard aspect describes something that will keep asking for attention; an easy one describes something that comes cheaply enough to be taken for granted. Both are information, not a sentence.
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