Star Sign Chart Calculator
Star sign chart calculator works out Zodiac sign and Sign glyph from Birth date. The default figures on this page give zodiac sign of Aries; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- Parsed 2000-03-21 as a Gregorian date: month 3, day 21.
- Matched month-day 03-21 against the twelve inclusive conventional ranges.
- 03-21 falls inside 03-21..04-19, which is Aries.
- Aries is a cardinal fire sign ruled by Mars.
Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
2 sources
What the star sign chart calculator calculates
Returns the western tropical sun sign for a birth date from the conventional fixed civil-date ranges, with the matched range and calculation basis shown.
How to use this star sign chart calculator
Enter Birth date. Zodiac sign updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Zodiac sign, Sign glyph and Conventional sign range.
The method follows Claudius Ptolemy, Tetrabiblos, Book I (translated F. E. Robbins, Loeb Classical Library 435) and Hong Kong Observatory, The 24 Solar Terms.
Research case zodiac-aries-start: first day of Aries example
With Birth date: 2000-03-21, the calculator returns Zodiac sign: Aries, Conventional sign range: 03-21..04-19. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Zodiac sign, Sign glyph and Conventional sign range. The inputs you can vary are Birth date.
Understanding Zodiac sign, Sign glyph and Conventional sign range
For entertainment and cultural interest. Astrology and numerology are traditional practices with no scientific basis for predicting events or describing a person; do not use them for health, financial or legal decisions.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I find my star sign chart?
Returns the western tropical sun sign for a birth date from the conventional fixed civil-date ranges, with the matched range and calculation basis shown. Open “How this is worked out” beside the result to see each step for your own figures.
What is the fakest star sign?
On the figures this page opens with, the zodiac sign is Aries. No single number fits everyone: it follows Birth date, so enter your own above and the answer updates as you type.
What are the top 3 luckiest zodiac signs?
It needs Birth date. Nothing else is required, and the figures stay in your browser.
What is the 3 most rarest zodiac sign?
The result gives Zodiac sign, Sign glyph, Conventional sign range, Calculation basis, Element and Modality, each labelled with its unit so the figure can be read on its own.
What information do I need for the star sign chart calculator?
You need Birth date. The page opens with default figures that give zodiac sign of Aries, so you can see the scale before entering your own.
What does this star sign chart calculator show?
It shows Zodiac sign, Sign glyph, Conventional sign range, Calculation basis, Element, Modality, Ruling planet and Polarity, with the working and any warnings for your entries.