Natal chart method and sources
A natal chart answers three positional questions: which sign and house each body occupies, and which aspects connect them. Positions are calculated astronomically; interpretation is a separate layer. This page first explains what the chart contains and how your details become a chart.
Three steps: enter, calculate, read
There are three steps from your details to a chart; we handle the calculation.
- 01You
Enter your birth details and place
Use a Gregorian or lunar date, ideally with the time to the minute, and a birthplace entered as a city or coordinates and time zone. A traditional two-hour birth period is too broad for the Ascendant and twelve cusps, which move roughly one degree every four minutes.
- 02Us
Calculate the chart
We calculate all ten longitudes, the Ascendant and MC, twelve cusps, and aspects together. The Calculation details panel lists the actual inputs. See Methods and validation for the zodiac, house-system, and node conventions.
- 03You
Follow the reading guide
The free chart has sections for personality traits, the chart itself, chart themes in everyday life, and the coming year. The Complete Natal Chart Reading ($7) adds personal interpretation by planet, house, and aspect. Explore the chart before deciding.
- For people who know their Sun sign and want to locate their Moon, rising sign, and other planets.
- For people comparing another chart and looking for clearly documented conventions.
- For people who want a free chart before deciding whether to purchase a detailed reading.
What is in a chart?
Each group of chart features has its own guide. Counts come from the underlying registry, and each entry links to further detail.
- 0112 signs
12 zodiac signs
Style of expression: the zodiac has twelve equal divisions, and each body occupies a sign.
Aries through Pisces, with solar ingress dates calculated for each year.
Explore the guide - 0210bodies
Ten planets
The forces involved: the Sun, Moon, and eight planets each represent a domain.
The Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn: planetary meanings and how calculations are checked.
Explore the guide - 031point
Rising Signs
The eastern horizon: the degree rising at birth, from which the houses begin.
How the rising sign is calculated and how it differs from the Sun sign.
Explore the guide - 0412 signs
Twelve houses
The setting: houses depend on birth time and place and shift within minutes.
The areas of life associated with each house, from the first to the twelfth.
Explore the guide - 055types
Aspects
Connections: two bodies form an aspect when their longitudes differ by a defined angle.
Conjunction, opposition, square, trine and sextile: the geometry and interpretation of the five major aspects.
Explore the guide
Methods and validation
Compare these five conventions before comparing charts from different services.
Different charts often reflect different methods rather than calculation mistakes. We state each choice and its basis:
- ZodiacTropical zodiac
- Measured from the vernal equinox, in the same frame as our validated ephemeris. Sidereal traditions use different origins; we do not adopt one here.
- House systemPlacidus, our chosen system
- Each position's diurnal and nocturnal semi-arcs are trisected, placing cusps at equal temporal divisions. Other systems, including whole-sign and Koch, are explicitly not adopted. We use one house system consistently rather than declare the alternatives wrong.
- Lunar nodesTrue nodes
- These can be compared directly with our reference ephemeris. We do not adopt the mean-node model, for which we do not have the same comparison.
- ValidationJPL Horizons
- The ten planetary positions are checked individually against JPL Horizons in sixty cases, with a maximum difference below eighty arcseconds. If a body is too close to a sign boundary for a confident classification, the chart says so.
- True solar timeNot applied to natal charts
- The cusp formula already uses longitude; applying a separate apparent-solar-time correction would count it twice. Daylight saving time is still removed where applicable, with automatic detection in the form.
Frequently asked questions
Three groups: birth details, interpretation, and settings and pricing.
Why is a precise birth time necessary?
A traditional birth-hour period covers two hours, while the Ascendant and house cusps move roughly one degree every four minutes. The Sun sign changes much more slowly, but a two-hour interval cannot locate the Ascendant and cusps precisely. If the time is uncertain, try the closest estimate; the Calculation details panel records the exact time used.
Can I use a lunar-calendar birthday?
Yes. We convert the lunar date to its Gregorian equivalent before calculating the chart. You do not need to look up the conversion yourself.
Are the Sun sign, Moon sign, and rising sign different things?
They answer three different questions. The familiar question about your zodiac sign usually refers only to the Sun. The Moon and Ascendant are separate positions and often occupy different signs in the same chart. The first step of the chart guide explains each one.
Is retrograde motion bad?
An average chart contains 2.3 retrograde planets, calculated by summing the measured rates for the eight planets that can turn retrograde. It is apparent motion seen from Earth, not an accident or a standalone negative prediction. The chart marks the motion as retrograde.
Why does my chart differ from another service's?
The usual causes are three methodological choices: tropical or sidereal zodiac, quadrant or whole-sign houses, and true or mean nodes. Our choices and reasons are explained under Methods and validation. The Calculation details panel records the inputs actually used. Compare those conventions before comparing results.
What is the difference between the free chart and the full report?
The entire chart, including positions, cusps, aspects, and calculation details, is free without registration. The Complete Natal Chart Reading adds personal interpretation by planet, house, and aspect. Its price is shown in advance: $7.