Guide
Your birth chart: what it shows and how it's calculated
What is a natal chart?
A natal chart, also called a birth chart, is a map of the sky at the exact moment and place you were born. It shows where the Sun, the Moon and the planets stood in the zodiac, which sign was rising on the eastern horizon – your Ascendant – and how the sky divides into twelve houses around you.
Astrologers read the chart as a symbolic portrait rather than a forecast. The planets describe different drives – the Moon your emotional needs, Venus the way you love, Mars the way you act. The signs describe the style in which each drive works, and the houses show the areas of life where it tends to play out. Read this way, a chart is a vocabulary for self-reflection, not a verdict.
What you need: date, exact time and place
Three details make a chart: your date of birth, the time as precisely as you know it, and your place of birth. The place sets two things: the coordinates that define the horizon and the time zone in force on that date, including daylight saving time. Historical time-zone rules are applied automatically, so a birth in Sofia in 1979 or in London in 1968 converts to universal time correctly.
- Date: day, month and year (1900 onwards).
- Time: from your birth certificate if possible; an approximate time still helps.
- Place: the town where you were born, not where you live now.
Why the birth time matters so much
The Earth turns once a day, so the whole zodiac passes over the horizon every 24 hours. On average the Ascendant moves about one degree every four minutes and changes sign roughly every two hours. At the latitude of Bulgaria, Aries and Pisces rise in just over an hour, while each sign from Leo to Scorpio takes about two and a half hours. House cusps move just as fast, so half an hour can shift a planet into the neighbouring house.
The planets move far more slowly: the Moon about half a degree an hour, the Sun about a degree a day. So a chart without a time still gives reliable planet signs, while the Ascendant, the Midheaven and the houses need the clock.
How we calculate your chart
Positions come from a modern astronomical ephemeris that our automated tests check against NASA JPL Horizons reference data; the planets agree to better than one arcminute. We use the tropical zodiac, as most Western astrologers do, Placidus houses – the most common house system – and the true lunar node. Above the polar circles, where Placidus is undefined, we switch to whole-sign houses and say so in the result.
Aspects use standard orbs, and the whole calculation takes our server well under a second.
How to read the chart wheel
The wheel is drawn the way astrologers read it: the Ascendant sits on the left, at 9 o'clock, and the houses are numbered counter-clockwise from there. The outer ring holds the twelve signs; each planet's glyph sits at its exact degree, and ℞ marks planets that were retrograde. The lines in the centre are aspects: blue and teal for flowing ones (trines and sextiles), red and pink for tense ones (squares and oppositions) and gold for conjunctions.
If you don't know your birth time
Tick "I don't know my birth time" and we calculate the chart for noon. Planet signs stay reliable and the aspects are close, but we leave out the Ascendant, the Midheaven and the houses rather than guess them. If the Moon changed sign that day, you'll see both possible signs and the exact local time of the switch.
It's worth looking for the real time: many birth certificates record it. Even an approximate time narrows the options.
Your privacy
This calculator needs no account. Your details reach our server only to calculate the chart and are not saved. To protect the service from abuse, we briefly keep a per-IP request counter in memory, never linked to your birth data. With a free account you can save the chart and get the full AI reading.