The method we use
The Star Chart uses Western tropical astrology and Placidus houses. It calculates positions for the Sun, Moon, and planets, then uses your birthplace and birth time to work out the Rising sign and house boundaries.
The time and place you enter
Enter the local date and time recorded for your birth, and choose your birthplace from the suggestions. Your current location and time zone don’t affect the calculation.
We use your birthplace to look up the time-zone and daylight-saving adjustment for the calculation. You don’t need to convert the time yourself.
Historical changes to a place’s time zone may not be reflected in your chart. Births near a clock change can also need closer checking.
Finding your zodiac signs
Your birth date and time let us find where the Sun, Moon, and planets were in the zodiac when you were born. Each position falls within one of the twelve signs.
Your birth time can determine your Sun sign near a sign change, so we calculate its position for that moment. A fixed list of calendar dates alone can miss that distinction.
How we find your Rising sign and houses
Your Rising sign, also called your Ascendant sign, is the sign on the eastern horizon when you were born. It depends on both your birth time and your birthplace.
Houses divide the chart into twelve areas. Their boundaries depend on your birth time and location. A planet’s position within those boundaries determines its house.
For births near the poles, we use Equal houses because Placidus can be unreliable there. Another site may handle these locations differently and show different house placements.
What if you don’t know your birth time?
You can enter 12:00 PM (noon) as an estimate. Your chart will be calculated for that time.
Your Rising sign and houses may be wrong because both depend on the time. The Moon can change signs during the day too. Treat any placement close to a boundary with caution; a noon estimate does not have the same accuracy as a recorded time.
Check your birth certificate or ask a family member for a recorded time. You can also contact the hospital where you were born. If you find a more reliable time later, create a chart with the corrected details. If you already purchased a guide, contact Support for help correcting it.
Why can two websites give different results?
Before comparing the interpretations, check the birth details and calculation settings. These are the most useful things to compare:
- Check that you entered the same date, local time, and AM or PM. Confirm the birthplace, including the city and country.
- Check how each site handles time zones and daylight saving, especially for births near a clock change.
- Check whether both sites use the same zodiac. Tropical and sidereal zodiacs use different reference points and can assign different signs.
- Compare the house systems. Placidus, Whole Sign, and Equal can put the same planet in different houses.
Matching those settings makes the comparison more useful, although calculations can still differ.
How the calculation becomes a reading
Once we have the positions, signs, and houses, we select written interpretations for your placements. People who share a placement can receive the same text for it.
Those interpretations use astrology, with questions and suggestions for self-reflection. The astronomical positions do not establish that a description is true of you. For help understanding and using your reading, see how your birth chart reading works.