How Is Astrology Calculated?

Astrology, an ancient practice that holds intriguing insights into our personalities and life paths based on the alignment of celestial bodies at the time of our birth. But have you ever wondered how these complex interpretations are calculated? In this article, we will take a closer look at the fascinating process behind astrology’s calculations, unveiling the mathematical calculations and planetary positions that form the foundation of this mystical art. Get ready to uncover the secrets behind the intricate calculations that shape our astrological readings.

What is Astrology

Astrology is a system of beliefs and practices that examines the relationship between the positions of celestial bodies and earthly events. It is based on the idea that there is a connection between the movements and positions of the planets, stars, and other celestial bodies, and the personalities, behaviors, and events on Earth. Astrology is often used to gain insights into individual characteristics, predict future events, and analyze compatibility between individuals.


Astrology is the study of how celestial bodies, such as the planets, stars, and moons, influence human affairs and earthly events. It involves interpreting the positions and movements of these celestial bodies in order to gain insights into human behavior, personality traits, relationships, and life events.

Brief History

The origins of astrology can be traced back to ancient civilizations, such as the Babylonians, Egyptians, and Greeks. These ancient cultures developed systems of astrology that were based on their observations of the night sky and the belief that there was a correlation between the movements of celestial bodies and human life on Earth. Over time, astrology spread to other parts of the world and evolved into different forms and practices. Today, astrology is still widely studied and practiced in various cultures around the globe.

Astrological Elements

Astrology consists of various elements that are used to analyze and interpret the influences of celestial bodies on human life. These elements include zodiac signs, planets, and houses.

Zodiac Signs

The zodiac signs are a division of the ecliptic, which is the apparent path of the Sun across the celestial sphere throughout the year. There are 12 zodiac signs, each associated with specific dates and representing certain personality traits and characteristics. The zodiac signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. These signs are believed to influence a person’s behavior, emotions, and overall disposition.


In astrology, planets are symbolic representations of various aspects of human life. Each planet is associated with specific energies, characteristics, and influences. The major planets used in astrology are the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Each planet represents different areas of life, such as ego (Sun), emotions (Moon), communication (Mercury), love (Venus), action (Mars), expansion (Jupiter), discipline (Saturn), innovation (Uranus), spirituality (Neptune), and transformation (Pluto).


In astrology, houses are divisions of the birth chart or natal chart that represent different areas of life. There are 12 houses, each associated with specific aspects of life, such as self-image, relationships, career, home, and spirituality. The position of planets within these houses is believed to influence the energies and experiences related to each area of life.

Natal Chart Calculation

A natal chart, also known as a birth chart, is a map of the positions of celestial bodies at the exact moment of an individual’s birth. It is calculated based on the birthdate, time, and location of an individual.

Birthdate and Time

To calculate a natal chart, the exact date and time of an individual’s birth are crucial. The date includes the day, month, and year, while the time includes the hour and minute. The accuracy of the birth time is important for determining the positions of the celestial bodies at the moment of birth.


The geographical location of an individual’s birth is also required for natal chart calculation. The latitude and longitude of the birthplace are used to determine the specific angles and positions of the celestial bodies in relation to the Earth.

Zodiac Sign Placement

By using the birthdate and time, astrologers determine the zodiac sign that the Sun was in at the moment of birth. The Sun’s position in the zodiac reflects a person’s core identity and represents their ego, vitality, and basic personality traits.

Planetary Positions

Astrologers also calculate the positions of other planets in relation to the zodiac signs. The planetary positions indicate additional influences on an individual’s personality, emotions, and behavior. Each planet is placed in a specific zodiac sign, revealing its unique impact on different aspects of life.

House Positions

By dividing the natal chart into 12 houses, astrologers determine which zodiac sign governs each house. This information provides insights into the specific areas of life that are influenced by the celestial bodies. The house positions provide valuable information about an individual’s relationships, career, family life, and personal goals.

Zodiac Sign Calculation

Zodiac signs are determined by the date range during which the Sun appears to move through each sign.

Date Range

Each zodiac sign has a specific date range associated with it. For example, Aries is associated with March 21st to April 19th, while Taurus is associated with April 20th to May 20th. The dates may vary slightly from year to year due to the Earth’s tilt and the precise moment of the Sun’s entry into each sign.

Sun Sign

The Sun sign, also known as the star sign, reflects the zodiac sign under which a person is born. It is determined by the position of the Sun at the time of birth. The Sun sign is often seen as the primary indicator of an individual’s personality traits, motivations, and basic characteristics.

Cusp Signs

Cusp signs occur when an individual is born on or near the transition between two zodiac signs. In such cases, the person may exhibit traits and characteristics of both signs. The exact influence of a cusp sign depends on the specific positions of the other celestial bodies in the birth chart.

Planetary Positions Calculation

Planetary positions are determined based on an ephemeris, a table or data set that provides the positions of celestial bodies at specific times.


An ephemeris is a valuable tool used by astrologers to determine the exact positions of the planets at specific moments in time. It provides precise information about planetary movements, allowing astrologers to accurately calculate placements for individual birth charts or to analyze planetary transits and aspects.


Transits refer to the current positions of celestial bodies in relation to an individual’s birth chart. By comparing the current planetary positions to the positions in the birth chart, astrologers can predict and interpret how these transits may influence an individual’s life experiences, emotions, and overall energy.

House Positions Calculation

House positions in astrology are calculated using various systems, with the Placidus system being one of the most commonly used methods.

Zodiac Circle

The zodiac circle is divided into 12 equal sections, each representing a house. Each house starts at a specific degree of the zodiac and covers 30 degrees of the circle. Astrologers calculate the cusp, or starting point, of each house based on the birth time and location.

Placidus System

The Placidus system is a popular method for calculating house positions. It divides the space between the celestial equator and the zenith into equal subdivisions, resulting in houses that vary in size depending on the latitude of the birth location. The Placidus system is believed to provide accurate results and is widely used by astrologers to interpret the influence of planets and signs on specific areas of life.

Aspects and Orbs

Aspects and orbs are used to determine the relationships and connections between celestial bodies in a birth chart.


Aspects refer to the angles formed between celestial bodies in the birth chart. These angles indicate how the energies of the planets interact and influence each other. Orbs, on the other hand, refer to the allowable margin of error applied when calculating aspects. The size of the orb determines how close or exact two planets need to be in order to form an aspect.


To calculate aspects, astrologers determine the angular distance between two celestial bodies in the birth chart. The most common aspects include conjunctions, oppositions, squares, trines, and sextiles, each representing different types of relationships and influences.


Aspects provide valuable insights into an individual’s personality, behavior, and life experiences. They indicate how different planetary energies blend together, creating unique dynamics and challenges in various areas of life. The interpretation of aspects is a complex process that requires astrologers to consider the specific planets involved, their signs and houses, and the aspects they form with other planets.

Astrological Tools and Software

Astrologers use a variety of tools and software to perform calculations and analyze birth charts.

Traditional Calculations

In the past, astrologers relied on manual calculations, such as using tables and mathematical formulas, to determine planetary positions, house placements, and other astrological elements. While traditional calculations are still used by some astrologers, they are time-consuming and require advanced mathematical skills.

Computer Programs

With the advancement of technology, astrologers now have access to sophisticated computer programs and software that can quickly and accurately calculate birth charts and analyze astrological elements. These programs often include features like ephemeris data, chart interpretation, and transit analysis. They make the process of astrology more accessible and efficient for both professional astrologers and enthusiasts.

Interpretation and Analysis

Interpreting and analyzing a birth chart requires a deep understanding of astrological principles and expertise in chart reading.

Chart Reading

Chart reading involves analyzing the positions of celestial bodies, the relationships between planets, and the overall patterns and themes in the birth chart. Astrologers consider the placement and aspects of planets, the influence of zodiac signs and houses, and the interactions between different astrological elements. This comprehensive analysis provides insights into an individual’s personality, strengths and weaknesses, relationships, and life experiences.

Astrologer’s Expertise

A skilled astrologer combines their knowledge of astrological principles with intuition and personal experience to provide accurate and meaningful interpretations. They can offer guidance, insights, and predictions based on the birth chart, helping individuals understand themselves better, make informed decisions, and navigate life’s challenges.


Astrology is a fascinating and ancient practice that explores the relationship between celestial bodies and human life. By examining the positions and movements of planets, zodiac signs, and houses, astrologers can provide valuable insights into individual characteristics, predict future events, and analyze compatibility between individuals. Whether you are a believer or a skeptic, astrology continues to captivate people’s curiosity and offers a unique lens through which to understand ourselves and the world around us.