Birth Chart Calculator
Type your birth date, time and place. You get the wheel, a positions table, the houses and the aspects, with all the working shown.
What a birth chart shows
A birth chart, or natal chart, is a map of the sky at the moment and place you were born. The outer ring holds the twelve signs. Inside sit the Sun, Moon and eight planets at their exact degrees, plus the north node and Black Moon Lilith in the table. The twelve houses divide the chart by the horizon and meridian, so they depend on time and place.
Astrology reads a chart in layers: which sign each planet is in, which house it falls in, and the aspects, the angles planets make to each other. A trine is read as ease, a square as tension. The aspect grid shows every pair within orb.
Placidus houses are the default. Above about 66 degrees latitude Placidus breaks down, and the chart switches to Whole Sign houses and says so. Without a birth time, houses and angles are hidden and the planets are given for noon.
What each part of the chart means
| Body | Changes sign every | Describes |
|---|---|---|
| Sun | About a month | Core identity, vitality |
| Moon | About 2.5 days | Feelings, needs, instincts |
| Mercury | 2 to 8 weeks | Thinking and talking |
| Venus | About 4 weeks | Love, taste, values |
| Mars | About 6 weeks | Drive, anger, desire |
| Jupiter | About a year | Growth, luck, belief |
| Saturn | About 2.5 years | Limits, duty, maturity |
| Uranus | About 7 years | Change, independence |
| Neptune | About 14 years | Dreams, ideals, confusion |
| Pluto | 12 to 30 years | Power, endings, renewal |
| Ascendant | About 2 hours | First impression |
| Midheaven | About 2 hours | Public direction, career |
Worked examples
- Born 1990-03-05 at 10:00 in New York: Sun at
14°46′ Pisces - The same chart's Ascendant:
05°32′ Gemini - Its aspects among Sun to Pluto, within the orbs:
14 - Born at noon on 1990-06-01 in Tromsø, at 69.6 degrees north, the house system used is
wholebecause Placidus does not work there. - Born 1999-08-11 at 11:03 in London, during the total solar eclipse: Moon at
17°43′ Leohalf a degree from the Sun.
How this is calculated
Sun to Pluto: apparent geocentric ecliptic longitudes of date from astronomy-engine. Nodes and mean Lilith: Meeus ch. 47 and 50. Ascendant and MC from apparent sidereal time and true obliquity. Placidus cusps by iterating the semi-arc condition (Whole Sign above the polar circle), Whole Sign and Equal on request. Aspects: conjunction 8, sextile 5, square 7, trine 7, opposition 8 degrees, Sun and Moon plus 2.