Natal Chart Calculator

A natal chart (or birth chart) maps the positions of the Sun, Moon, and planets along the ecliptic — the apparent path of the Sun across the sky — at the exact moment of birth. The ecliptic is divided into twelve 30° segments called the zodiac signs. Each planet's position in a sign is interpreted in terms of that sign's element (Fire, Earth, Air, or Water) and modality (Cardinal, Fixed, or Mutable).

Sun sign is determined by the Sun's ecliptic longitude — calculated from Meeus's solar position formula using the mean longitude, mean anomaly, and equation of the center. It changes roughly once a month as Earth orbits the Sun.

Moon sign requires your birth time because the Moon moves ~13° per day — crossing a sign roughly every 2.5 days. Lunar longitude is computed from Meeus's full Chapter 47 series — 60 periodic terms for the Sun's pull (evection, variation, annual equation and the rest) plus corrections for Venus, Jupiter and Earth's flattening. Checked against JPL's Horizons ephemeris for dates from 1760 to 2190, it is within ±0.05°.

Rising sign (Ascendant) is the zodiac sign rising over the eastern horizon at birth. It requires both birth time and location because it depends on Local Sidereal Time — Earth's rotational angle relative to the stars. The Ascendant shifts by roughly 1° every 4 minutes, cycling through all 12 signs in ~24 hours. Whole Sign houses are used here: the Rising sign occupies the entire 1st house, and each subsequent sign is the next house.

Planet positions are computed via Kepler's equation from JPL's approximate Keplerian elements (Standish & Williams, valid 3000 BC – AD 3000), including the long-period corrections for the mutual pull of Jupiter, Saturn, Uranus and Neptune. The geocentric ecliptic longitude is derived by subtracting Earth's heliocentric position from the planet's heliocentric position. Checked against JPL's Horizons ephemeris for dates from 1760 to 2190, Mercury, Venus and Mars are within ±0.1° and Jupiter through Neptune within ±0.5°.

Astrology is for entertainment and self-reflection only. Planetary positions are astronomical facts; their astrological interpretations are a cultural tradition, not empirical science.

Link to this tool with values filled in

Everything after the # stays in your browser — it is never sent to a server — so a link like this opens the tool ready to go without the values travelling anywhere but the address bar:

https://crunchify.net/tools/astrology#date=1990-07-14&time=08%3A30&lat=32.7767&lon=-96.797&tz=America%2FChicago&place=Dallas%2C%20US

Join the settings with &, and percent-encode each value so that spaces, newlines and any #, &, = or % inside one do not break the link. Leave a setting out to accept its default. If a setting is not recognised, the page says so rather than quietly ignoring it.

• date (also birthdate or dob) — text, up to 10 characters, required. Birth date as YYYY-MM-DD.
• time (also birthtime) — text, up to 5 characters, defaults to 12:00. Birth time as HH:MM on a 24-hour clock, in the zone given by `tz`. The rising sign depends on it, so an unknown time makes that placement meaningless rather than approximate.
• lat (also latitude) — a whole number from -90 to 90. Latitude in decimal degrees, north positive. For example 32.7767 for Dallas.
• lon (also lng, long or longitude) — a whole number from -180 to 180. Longitude in decimal degrees, east positive. For example -96.797 for Dallas.
• tz (also timezone or zone) — text, up to 64 characters. IANA time zone the times should be shown in, such as America/Chicago. Omit it and the reader’s own zone is used, named on the page so it is never ambiguous.
• place (also name, city or location) — text, up to 80 characters. What to call the coordinates on the page, such as “Dallas, US”. Display only — it does not move the location.

The tool reads these on arrival but never writes them back, so what you type here stays out of your browser history.