Natal Chart Calculator

That is three signs out of thirteen bodies. What comes after is the reason people build a chart at all: where each planet sits, which houses they fell into and how they answer each other - and Luna reads that aloud, in plain words.

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What the calculation needs

Three things: date, time and place of birth. The date fixes where the planets stood, the time fixes the rising sign and the houses, the place supplies coordinates that both depend on. A calculation without the time still works, it simply comes back without a rising sign: that point travels the whole zodiac in a day and changes sign roughly every two hours.

Birth times usually live on a birth certificate, a hospital record or a mother's medical file. If it is nowhere to be found, running the calculation anyway is worth it: the Sun and almost always the Moon come out reliably, and a borderline Moon gets flagged.

Pick the city from the suggestions rather than typing it freely: the maths runs on coordinates, and the time zone is filled in automatically - the zone that applied in that place in that year, not the one that applies today. For births before the middle of the last century this matters more than it sounds: zones and daylight saving rules moved around repeatedly.

Why these three signs

Astrologers call them the big three, and not for the ring of it: between them they answer three different questions about a person, and none of the three works alone.

The Sun is what someone gets up for: the core, the will, what feeds them. It is the only one of the three most people already know, because it needs nothing but a date.

The Moon is what happens inside when nobody is watching: how a person settles, how they take things, what they need in order to feel at home. This is where people tend to recognise themselves, more often than in the sun sign, and it usually surprises them.

The rising sign is the outside in the first minutes of meeting: manner, tempo, first impression. It also sets where the houses begin, so a chart without it has no frame.

After that come the other ten bodies, the twelve houses and the aspects between them - and that is where a chart stops being three words and starts describing one particular person.

Natal chart or destiny matrix

They get mixed up often, and they are different systems calculated in different ways.

What goes in. A natal chart needs date, time and place. The destiny matrix needs only a date.
Where the numbers come from. The chart is built from the real position of the planets at the moment of birth, out of ephemeris tables. The matrix is built from the digits of the date, by arithmetic.
What you end up with. A chart gives 13 bodies across signs and houses plus the aspects between them. A matrix gives 22 arcana laid out on an octagram.
How much two people differ. People born on the same day share an identical matrix. Charts they do not share: time and place pull the rising sign and the houses apart.

Nothing about them contradicts. They answer different questions, and plenty of people read both.

Frequently asked questions

Is the natal chart calculation free?

The three main signs - Sun, Moon and rising - are calculated free and without an account. The full chart, with planets across houses and the aspects between them, is read in the Luna app.

What if I do not know my exact birth time?

Run it without one. The Sun and almost always the Moon come out reliably; the rising sign does not, and in that case we leave it out rather than guessing. If the Moon changed sign that day, we say so.

How much does the exact minute matter?

For the Sun, not at all. For the Moon, rarely. For the rising sign it decides: it moves about a degree every four minutes, so being half an hour off can change the sign, while two minutes almost never will.

My town is not in the suggestions.

Use the nearest large city. Within a hundred kilometres the rising sign barely shifts and the time zone is the same. Exact coordinates matter for house cusps, but not enough to go hunting for a village.

Why does another site give me a different rising sign?

Usually the time zone or the house system. We apply the zone that was in force at that place in that year and use Placidus houses, the most common system. A site that applies today’s zone will be off by exactly an hour.

Does a natal chart predict anything?

No. It describes where the bodies stood at the moment of birth and how that is conventionally read. There are no dates or events in it, and we do not invent any.

The calculation is for entertainment and self-reflection.

What comes next

A full chart is 13 bodies, 12 houses and the aspects between them. In the Luna app all of it is read out loud: the big three, the personal planets, the generational ones and the tightest aspects - with your earlier conversations remembered.