How We Calculate Rising Signs

A rising sign is the zodiac sign on the eastern horizon at the exact moment and place of your birth. Here is exactly what we need and how the calculation works.

Step 1: Birth date

The full date of birth — day, month, and year. Used to calculate planetary positions and the Julian Day Number.

Step 2: Birth time (to the minute)

The ascendant moves approximately one degree every four minutes. An error of 30 minutes can mean a completely different rising sign. Find your exact birth time on your birth certificate.

Step 3: Birth place

The city where you were born. Used to determine geographic coordinates (latitude and longitude) and local time zone.

The calculation process

  1. Convert local birth time to UTC using time zone and daylight saving data
  2. Calculate the Julian Date for the birth moment
  3. Compute Greenwich Sidereal Time (GST)
  4. Convert to Local Sidereal Time (LST) using birth longitude
  5. Find the ecliptic degree rising on the eastern horizon (the ascendant)
  6. Map that degree to a zodiac sign

Calculate your rising sign →