How to use
- 1Enter your date and local time of birth, or tick “birth time unknown”.
- 2Search for your birth city, or enter latitude, longitude and time zone.
- 3Choose a house system: Placidus (default) or Whole Sign.
- 4Read the chart wheel, the table of positions and the list of aspects.
What your natal chart shows
A birth chart is a map of the sky at the moment you were born. The calculator shows the sign, degree and retrograde status of the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, plus the North Node (true node). It also calculates the Ascendant (rising sign) and the Midheaven (MC), divides the chart into 12 houses and draws everything on an SVG chart wheel with glyphs and aspect lines. Your Venus and Mars signs are highlighted with short traditional meanings for love and drive.
Houses: Placidus or Whole Sign
Placidus, the default, is the house system most widely used in modern Western astrology; it divides the sky by time and gives houses of unequal size. Whole Sign houses are older and simpler: each house is one complete sign, starting with the sign of the Ascendant. Above about 66° latitude, near the polar circles, Placidus cannot be calculated for some times of day, so the tool switches to Whole Sign automatically and tells you so.
Aspects and orbs
Aspects are angles between planets. The calculator lists the five major ones, conjunction (0°), sextile (60°), square (90°), trine (120°) and opposition (180°), together with the orb, which is how many degrees the actual angle is from exact. A smaller orb is traditionally read as a stronger aspect. The same aspects are drawn as lines inside the chart wheel, so patterns are easy to spot.
Unknown birth time, privacy and accuracy
If you do not know your birth time, choose “birth time unknown”: the chart is calculated for noon, houses, Ascendant and MC are hidden, and the Moon may be off by up to about 6°. All positions are computed in your browser with the open-source astronomy-engine library, and nothing is stored or uploaded. Please keep in mind that astrology has no scientific basis; the chart is astronomically accurate, but its interpretation is a tradition for entertainment.
Frequently asked questions
What do I need to calculate my birth chart?
Your date of birth, the time as precisely as possible and the place of birth. The time is needed for the houses, Ascendant and Midheaven.
What if I don’t know my birth time?
Tick “birth time unknown”. The planets are calculated for noon; houses, Ascendant and MC are hidden because they change every few minutes.
Which house system should I choose?
Placidus is the most common choice today. Whole Sign is popular in traditional and Hellenistic astrology. Try both and compare.
What does retrograde mean in my chart?
A planet is marked retrograde when, seen from Earth, it appeared to move backwards through the zodiac at your birth. It is an optical effect of the orbits.
Is my birth data saved?
No. Everything is calculated in your browser, and your data is never sent to a server.
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