Birth Chart Calculator

Birth chart calculator with houses, rising sign and aspects

This free birth chart calculator turns a date, time and place of birth into a complete natal chart: the Sun, Moon and rising sign, every planet from Mercury to Pluto, the lunar nodes, the Midheaven, twelve house cusps in Placidus, whole-sign or equal houses, the major aspects, and a chart wheel you can download. The positions are where the bodies actually stood at that moment, and the chart is drawn entirely in your browser.

Historical births are handled properly: the time-zone database knows old daylight-saving rules, and a local mean time option covers records from before standard zones existed. If you only know the date, tick Birth time unknown and you still get the Sun, Moon and planets for noon that day. Astrology is a cultural tradition rather than a science, and this page treats it that way: the chart is for tradition and entertainment, not prediction or advice.

How to use the Birth Chart Calculator

1. Enter the Date of birth and Time of birth (24-hour clock), or tick Birth time unknown.
2. Pick the Birth city, or type Latitude and Longitude and choose the Time zone. For births before about 1890, set Clock used to local mean time when the record is in local time.
3. Choose Houses (Placidus, whole sign or equal), the Zodiac (tropical, or sidereal with the Lahiri ayanamsa) and the lunar Node (true or mean).
4. Read the Sun, Moon and rising sign in the panel, then the planets, house cusps and aspects in the tables. A note appears when something sits within 0.2° of a sign boundary.
5. Download the wheel as SVG or PNG, or copy the whole chart as text.

Birth Chart Calculator features

How the positions are calculated

The birth time is converted to Universal Time with the chosen clock, then to a Julian Day and to Terrestrial Time with the Espenak–Meeus ΔT polynomial. The Sun’s apparent longitude follows Meeus chapter 25 and the Moon chapter 47 (ELP-2000/82 truncated to its largest terms, about 10 arc-seconds). Mercury to Neptune use Paul Schlyter’s orbital elements with the major perturbations, good to one or two arc-minutes; Pluto uses Meeus’ series (chapter 37), accurate to seconds of arc for 1885–2099 and flagged as approximate outside that range. The true node is the osculating node of the Moon’s instantaneous orbit, as in Swiss Ephemeris. Sidereal positions subtract the Lahiri ayanamsa — 23.857092° at J2000 plus the IAU 2006 precession rate — which matches Swiss Ephemeris tables to within an arc-second.

The Ascendant is the ecliptic degree rising in the east, from local sidereal time, latitude and the obliquity; the Midheaven is the degree on the meridian. Placidus cusps 11, 12, 2 and 3 are found by iterating the point whose semi-arc is trisected, the method behind every published table of houses. The same engine powers the kundli generator, which applies the sidereal zodiac and whole-sign houses of Indian astrology.

Reading the chart

Each planet’s row shows its position to the arc-second, its house under the selected system, whether it was retrograde (℞) and a note when it lies within 0.2° of a sign edge, close enough that a slightly different birth time could change the sign. The house table lists all twelve cusps with the angles labelled AC, IC, DC and MC. In the aspect list, “applying” means the faster body was still moving towards the exact angle at birth.

Birth chart without a time

Tick Birth time unknown and the planets are computed for noon local time. The Sun and slow planets barely move in a day, so their signs are reliable; the Moon travels about 13° a day, so if its noon position is within 6–7° of a sign boundary it could be in either sign, and the note under the panel tells you so. The rising sign, Midheaven and houses depend on the hour and are not shown. For the Sun sign alone the zodiac sign calculator is quicker, and the moon phase calculator shows the lunar phase on the day.