Cast a natal chart
A birth chart is a map of where everything was at the moment you arrived. Most free calculators approximate it. This one works it out properly, then draws the wheel and tells you what each placement is doing there.
- 01
Your moment, resolved
Your birth date and clock time are converted to a precise instant using the time-zone rules that were actually in force at that place on that day — including wartime measures and abandoned daylight-saving experiments.
- 02
The bodies, computed
Solar and lunar longitudes follow Meeus; the planets are propagated from Keplerian elements and reduced from heliocentric to geocentric. Typical error is well under a tenth of a degree.
- 03
The angles, derived
The Ascendant comes out of sidereal time, the obliquity of the ecliptic and your latitude. Houses are equal from the Ascendant — the system that stays sane at high latitudes.
Frequently asked questions
What is an astrological natal birth chart?
A natal birth chart is an astronomical map of the sky calculated for the exact date, time, and geographic coordinates of your birth. It calculates the precise geocentric ecliptic longitudes of the Sun, Moon, and nine planetary bodies, along with the Ascendant (rising sign), Midheaven, twelve houses, and angular aspects.
Do I need an exact birth time to calculate my birth chart?
A birth date and city provide accurate positions for the Sun and slower-moving outer planets. However, the Ascendant (rising sign) and twelve astrological houses rotate a full 360 degrees every 24 hours (roughly 1 degree every 4 minutes). An exact birth time is required to compute your true rising sign and house cusps.
Which house system does this natal chart calculator use?
This calculator uses the Equal House system measured from the exact degree of the Ascendant. Equal houses avoid the mathematical distortion and extreme cusp skew that quadrant systems (like Placidus) experience at higher geographic latitudes above 50° North or South.
How are the planetary coordinates computed?
Planetary longitudes are derived directly from astronomical ephemeris equations after Jean Meeus and JPL Standish Keplerian orbital elements (fitted for 1800–2100). Coordinates are reduced from heliocentric to geocentric apparent positions and corrected for historical timezone variations.
Can I export or copy my chart data to ChatGPT or AI assistants?
Yes. Click 'Copy for AI / Notes' beneath your calculated chart to copy a clean, structured plaintext summary of all your planetary degrees, signs, and angles, formatted specifically for input into AI assistants or personal journal notes.
Looking for one thing in particular?
The full chart answers everything at once. These answer one question properly, with the interpretation that goes with it.