Birth chart calculator
Your free natal chart: every planet by sign, degree and house, the aspects between them, and a plain-English reading. Calculated privately in your browser.
Enter your details and your wheel appears here: the zodiac on the outer ring, houses inside, planets placed to the degree.
How to read your birth chart
A birth chart is a map of the sky from the exact spot where you were born. Picture yourself at the centre of the wheel looking south: the left edge is the eastern horizon (the Ascendant), the top is the highest point the zodiac reached overhead (the Midheaven).
- Outer ring: the 12 signs. Each sign is a 30° slice of the ecliptic, the Sun’s yearly path, starting at Aries 0° where the Sun crosses the celestial equator in March.
- Inner ring: the 12 houses. Houses divide the sky by the Earth’s daily rotation, so they depend on birth time and place. Each governs an area of life, from self (1st) to the hidden (12th). See what each house means.
- Glyphs: the planets. The sign a planet sits in describes how it acts; the house says where in life it shows up.
- Lines: the aspects. Blue lines are harmonious angles (trines and sextiles), red lines are tense ones (squares and oppositions).
Most people start with the Big 3: Sun (identity), Moon (emotional needs) and Rising sign (how you come across). Then Mercury, Venus and Mars describe how you think, love and act.
What you need
- Date of birth. Enough for your Sun sign and most planets.
- Time of birth, ideally from a birth certificate. The Ascendant moves about 1° every 4 minutes, so a time off by an hour can change your rising sign and every house.
- Place of birth. Used for latitude and longitude, and to look up the historical time zone and daylight-saving rules, which the calculator applies automatically.
Where the numbers come from
Positions are computed on your device with Astronomy Engine, which implements the VSOP87 planetary theory and the ELP/MPP02 lunar theory, apparent geocentric positions of date. The Ascendant, Midheaven and Placidus cusps are solved from local sidereal time and the obliquity of the ecliptic, the same method described in standard references such as Jean Meeus’ Astronomical Algorithms.
Questions people ask
Is this birth chart calculator free?
Yes. The full natal chart, placements table, houses, aspects and written interpretations are free with no sign-up. The optional AI reading is also free, with a small per-visitor limit to keep costs sane.
How accurate is it?
Planet positions come from Astronomy Engine, an open-source library built on the VSOP87 and ELP lunar theories that agrees with NASA JPL ephemerides to within about an arcminute for these dates. That is far finer than the one-degree precision astrologers work with, and matches what Swiss Ephemeris-based sites show.
What if I don’t know my birth time?
Untick “I know my birth time”. We calculate for local noon: your Sun and planets will still be right (except on the rare day one changes sign), the Moon may be off by up to about 7°, and the rising sign and houses are omitted because they depend on the exact minute.
Which zodiac and house system do you use?
The tropical zodiac used in Western astrology, with Placidus houses by default. You can switch to Whole Sign or Equal houses above the chart.
Is my birth data stored?
The chart is computed in your browser. Only the city search is sent to Open-Meteo’s geocoding service, and chart data is sent to our AI endpoint only if you press the AI reading button. Saved people live in your browser’s local storage, which you can clear on the privacy page.
What is the difference between a birth chart and a natal chart?
None. “Birth chart” and “natal chart” are two names for the same map of where the Sun, Moon and planets stood, seen from your birthplace, at the moment you were born.