Birth Chart Calculator (Natal Chart)

A birth chart (natal chart) is a map of where the Sun, Moon and planets stood in the zodiac at the moment you were born, seen from your birthplace. This calculator works it out in your browser from your birth date, local time and city: your Sun, Moon and rising sign, every planet with its sign, degree and house, the major aspects between them and a printable chart wheel. Astrology is a tradition of interpretation, not a science — the positions are real astronomy, the meanings are for reflection and entertainment only.

How to use this tool

1. Enter your birth date and the local clock time from your birth certificate (daylight saving is handled automatically).
2. Choose the birth city, or “Other place” and type latitude, longitude and time zone.
3. Pick a house system — Placidus is the most common in Western astrology; Whole Sign is the oldest.
4. Press the button to draw the chart; save the wheel or copy the tables.

Formula

Ascendant = atan2(cos θ, −(sin θ cos ε + tan φ sin ε))

θ is the local sidereal time (Greenwich sidereal time + east longitude), ε the obliquity of the ecliptic and φ the latitude. Planet longitudes come from orbital elements solved with Kepler's equation, converted from heliocentric to geocentric and to the equinox of date. Placidus cusps divide each point's diurnal and nocturnal arcs into thirds.

Example

For 15 June 1990, 12:00 in New York (16:00 UTC), the Sun is at about Gemini 24°, and the Ascendant falls in Virgo, because at local noon the Sun sits near the top of the chart (the Midheaven) and the rising sign is roughly a quarter of the zodiac behind it.