Birth chart calculator

Give your birth date, time and city, and you get the whole chart: the wheel, every planet with its sign, degree and house, the house cusps, every aspect with its orb, and a read on the chart’s shape. If you do not know your birth time, say so — the tool answers that case properly instead of guessing. Free, no account, nothing stored.

What it does, and why it is here

Casting a chart is three separate calculations that all have to agree. Where the planets were, which needs an ephemeris. Where the horizon and the meridian were, which needs your latitude and longitude to the minute. And what local time your birth certificate actually meant — the hardest of the three, because it depends on the time zone rules and the daylight saving in force at that place on that date, and those have changed repeatedly within living memory.

That last one is why the form asks for a city rather than a country or an offset. Picking a city fixes the coordinates and the historical zone in one gesture, and it is where most disagreements between two charts of the same person come from.

The other thing this page tries to do is be honest about its conventions. It says which house system it used and lets you change it — two charts of the same birth genuinely differ when one is Placidus and the other whole sign, and neither is wrong. And when the birth time is unknown, it does not quietly cast a chart for noon and present it as yours.

What you fill in

• Date and time of birth — local time at the place of birth. The time zone comes from the city, historical daylight saving included.
• City — type and pick; the coordinates fill themselves in. A city rather than a country, because one country can hold several zones and several hours of longitude.
• House system — Placidus (what most charts use), Koch, equal, or whole sign. Worth knowing: whole sign and equal houses exist at every latitude, while Placidus and Koch do not work beyond the polar circles — and the tool says so rather than returning nonsense.
• “I don’t know the birth time” — tick it and the tool sweeps the entire day at your birth place instead of casting a chart at an hour nobody knows.

What you get back

• The wheel, drawn, with the placements around it.
• Planetary positions — each body with its sign, its exact degree, its house, and whether it was retrograde at birth.
• House cusps — where each of the twelve begins, in the system you chose, named in the answer so the chart can be compared with another honestly.
• Every aspect, with its orb, so you can sort the exact contacts from the loose ones yourself.
• Elemental and modal balance — fire, earth, air, water; cardinal, fixed, mutable — with the dominant element named.
• The shape of the chart — the Jones pattern, the split of planets above and below the horizon and east and west of the meridian, the most aspected planet with its count, any named aspect patterns, and the list of bodies retrograde at birth. This is the part that says something about the chart as a whole rather than point by point.
• Without the birth time, when you ticked the box — the rising sign hour by hour, as spans with a from and an until. The Sun keeps its sign all day and the Moon nearly always does; it is the ascendant that moves, roughly every two hours. If you know it was “some time in the morning”, you read the matching span, and you have most of what an exact time would have given you.

What it does not do

It calculates; it does not interpret. There is no paragraph telling you what Mars in the seventh house means about your marriage, and no personality summary generated from your placements. What comes back is the chart itself, in a form you can read or take to someone who reads them.

It does not keep anything either: your birth date, time and city are used to compute the chart and then forgotten — not stored, not attached to an account, and never written into a shareable address.

And it is tropical, not sidereal. Western astrology measures from the equinox rather than from the constellations, which is why your Sun sign here differs from a Vedic chart by about 24 degrees. Neither is a mistake; they are two different zodiacs.

How much the birth time actually matters

So “I don’t know my birth time” costs you the houses and the angles, and nothing else. That is worth knowing before paying for a rectification: half the chart is unaffected, and the hour-by-hour ascendant table narrows the rest as far as your memory allows.

Questions

Is it free?

Yes. No account, no e-mail, no upsell.

Do you store my birth details?

No. They are used to compute the chart and then forgotten — not stored, not logged, not attached to any identity, and never put in a link.

I do not know my birth time. Is the chart useless?

No — tick the box. You keep the Sun, the Moon, every planet and every aspect between them; you lose the ascendant, the Midheaven and the houses. The answer then lists the rising sign hour by hour, so a rough memory of the time is enough to narrow it.

Where can I find my birth time?

On the long-form birth certificate in most countries, which is usually obtainable from the registry of the place of birth. Hospital records are the other route.

My chart disagrees with another site. Which is right?

Check three things in order: the house system, the time zone used for your birth date, and whether the other site assumed noon because you left the time out. Almost every disagreement is one of those, and the first two are stated in this answer so they can be compared.

Which house system should I choose?

Placidus if you have no opinion — it is what most Western charts and most books assume. Whole sign is the older system and is having a revival; it also behaves at every latitude, which Placidus does not.

What is a rising sign, exactly?

The zodiac sign that was climbing over the eastern horizon at your birth. It sets where the twelve houses begin, which is why it needs the time and the place rather than just the date.

Can I get a chart for a date in the future?

Yes. The ephemeris does not care which direction you ask in — a chart for a future moment is how an event or an election is looked at.

Sources and further reading

• Houses — the systems, and how they differ.
• Aspects — the angles, and what an orb is.
• Tropical zodiac — why it differs from the sidereal one.