Birth chart calculator

What a birth chart shows

A birth chart, also called a natal chart, is a map of the sky at the minute you were born, seen from the place you were born. It records which zodiac sign each planet stood in, how the planets were angled to one another, and which part of the sky was rising on the eastern horizon.

Astrologers read it as a portrait drawn in symbols: the Sun for your core purpose, the Moon for your emotional needs, Venus for what you love and value, Mars for how you act, and so on through the outer planets. It describes tendencies, not fixed events, and it is one input among many when you think about your life.

What you need

• Date of birth. Enough on its own for the sign of every planet except, on some days, the Moon, which changes sign every two to three days.
• Time of birth. Needed for the rising sign (Ascendant), the Midheaven and the houses. The sky turns 1 degree every 4 minutes, so the rising sign changes about every two hours on average and the house cusps move with every minute. A birth certificate or hospital record is the best source.
• Place of birth. Sets the horizon the chart is drawn from and the time zone, including daylight saving time in force that day. The calculator finds both from the city you choose.

No time? Tick "I don't know my birth time". You still get every planet's sign and the aspects between them, with a note wherever the sign could have changed during the day.

How to read the wheel

The outer ring holds the 12 signs. The inner ring is divided into 12 houses, the areas of life the chart is read through: self, money, communication, home, creativity, work, partners and so on round to the twelfth house of rest and the hidden.

The horizontal line is your horizon: its left end is the Ascendant (AC), the sign rising in the east at your birth, and its right end the Descendant (DC). The vertical line runs from the Midheaven (MC), the top of the sky, down to the IC beneath your feet. Planets sit at their exact degree, and the colored lines across the middle are aspects: blue for the flowing ones (trines and sextiles), red for the tense ones (squares and oppositions).

Your big three

Most people start with three placements. The Sun sign is the one horoscopes use, read as your core self and what you aim for. The Moon sign is read as your emotional nature: what comforts you and how you react. The rising sign (Ascendant) is read as the way you meet the world and the first impression you give.

Two people with the same Sun sign can read very differently once the Moon and the rising sign are added, which is why a full chart says more than a sun sign column.

From your birth chart to your map

This is where a birth chart and astrocartography meet. The same planets that sit in your chart's houses were also overhead, rising, setting or underfoot somewhere on Earth at the moment you were born. Draw those places and you get four lines for each planet: the MC, IC, AC and DC lines.

Below your chart, the calculator lists the biggest city near each planet's MC and AC lines. Open the map to see every line, or recast your chart for a city you are thinking of with the relocation chart: the planets stay the same, the rising sign, Midheaven and houses change.

House systems

Astrologers do not agree on one way to divide the houses. Placidus is the most common in Western astrology and divides the sky by time. Whole Sign is the oldest: each house is one whole sign, starting with the rising sign. Equal makes every house 30 degrees from the Ascendant. Planet signs and aspects are the same in all three; only the house a planet falls in can change. Close to the poles Placidus cannot be drawn, and the calculator says so and uses Whole Sign instead.

How it is calculated

Planet positions come from the same engine as the map, checked against NASA JPL Horizons; see the method page. The chart is tropical (the zodiac Western astrology uses, tied to the seasons) and geocentric. Everything runs in your browser: your birth details are not sent to a server. A copied link carries them after the # sign, which browsers never send to a website, so share it only with people you trust.