Free Birth Chart With Calculated Positions

What is a birth chart?

A birth chart is a map of the sky for one moment and place: where the Sun, Moon and planets stood, seen from the birthplace at the minute of birth. The positions are astronomy; what they are taken to mean is astrology, which is interpretation.

What your birth chart shows

For a birth date, time and place, the chart calculates:

• the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, and the lunar nodes, each as a sign and a degree in the tropical zodiac;
• the Ascendant and Midheaven, the two angles set by the birth time;
• twelve house cusps, in the Placidus house system;
• the aspects between all of these, each with its angle and its orb.

How to read your birth chart

The traditional shorthand, a convention rather than a measurement: the planet is what, the sign is how, the house is where, and an aspect is the relationship between two planets. Start with your Sun, Moon and rising sign, then the aspects with the smallest orb. A step-by-step guide works through a full example.

Calculated positions vs. astrological interpretation

The measurable part is arithmetic: the planets’ positions, the angles, the house cusps, each aspect’s angle and orb, and the times. They come from a published astronomical engine, and every number is shown so it can be checked.

What a planet stands for, what a sign or house means, what an aspect does: that is interpretation. They are not the same thing, and this page says which is which.

Why birth time matters

The birth time sets the Ascendant, the degree rising in the east, and with it the Midheaven and where the twelve houses begin, which the house system divides.

Time zones and daylight saving have changed repeatedly, and a chart cast with today’s offset for a birth in 1974 is wrong by an hour — which moves the Ascendant by about fifteen degrees on average, but the actual change can be much smaller or much larger depending on latitude and which sign is rising. A birth time the clocks repeated or skipped is asked about rather than guessed. Clock times are converted using the international time zone database. Historical timezone records are strongest from 1970 onward; earlier records can be less certain, particularly where local clocks differed from a region’s recorded standard.

What if I don’t know my birth time?

Without a time, the chart is worked out across every real moment of your birth date. Each planet shows the whole degrees it covered that day, such as 14–16° Leo, never an exact position; one that changed sign shows both signs, as the Moon often does. Aspects are certain when they held all day and possible when they depend on the hour. The Ascendant, Midheaven and houses need a time and are left out; no rising sign is guessed. See without a birth time.

Birth chart FAQ

What is a birth chart?

The calculated map of the sky at the moment and place of birth; the meanings read into it are interpretation. See what a birth chart is.

What does this calculator work out?

The Sun, Moon, eight planets and the lunar nodes by sign and degree, the Ascendant and Midheaven, twelve Placidus house cusps, and every aspect with its orb, at the exact universal time of birth. It names its engine and version.

Is it free, and do I need an account?

Yes, and no. The chart is free, needs no account or email, and nothing you type is stored. An account adds the dated stretches ahead and a record of how they went (how it works, what is free).

What are houses, and what are aspects?

Houses are twelve divisions of the sky counted from the eastern horizon, read as areas of life; they need a birth time, and the 12 houses explains each one. Aspects are the angles between two points: calculated, then interpreted.

How exact does my birth time need to be?

To the minute. An hour moves the Ascendant by about fifteen degrees on average and can change the rising sign and every house; a few minutes rarely matter unless a sign boundary is close.

What if I don’t know my birth time?

Tick the box: the chart is worked out across the whole birth date, with whole degrees, both signs where a planet changed sign, certain or possible aspects, and no Ascendant or houses, nothing guessed. See without a birth time.

Why can two birth-chart calculators give different results?

Rarely the arithmetic: modern ephemerides agree closely on the planets. The differences are choices: the house system, the orbs, the zodiac, the time-zone rules used for the birth date, rounding, and what is done without a birth time. The comparisons show them for other apps, and a longer explanation shows how large each difference can be.