Zodiac Sign Calculator

This zodiac sign calculator finds your Western sun sign from your date of birth. You'll see the sign, its date range, element, modality and rulers, the opposite sign, and how many days your birthday sits from the nearest sign change.

Calculation and content reviewed by EZ Calculators Editorial Team on October 5, 2026.

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Build the scenario below, then calculate for a complete result report.

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Lookup modelPopular Western tropical calendar ranges

This date-only lookup does not calculate an ephemeris, astronomical constellation, Moon sign, rising sign, or birth chart.

AriTauGemCanLeoVirLibScoSagCapAquPis

Date of birth

Boundary alert

The boundary alert tells you when the selected date is close to a fixed calendar transition. It does not resolve the exact Sun position for a particular birth time and place.

What is my zodiac sign?

Your sun sign comes from the date range your birthday falls in. Born January 15, you're a Capricorn, because Capricorn runs from December 22 to January 19. Born January 20, you're an Aquarius. Born October 20, you're a Libra, three days before Scorpio begins on October 23. Enter your birthday to see your sign and how close the next one is.

How to use the zodiac sign calculator

Enter your birth date and press Find zodiac sign. The year doesn't change your sign in this lookup, but it lets the calculator show the weekday you were born and count days within your sign's range.

The boundary alert sets how close a birthday must be to a sign change before you get a heads-up. Three days is the default. You can pick the exact date only, or 1, 5 or 7 days.

Enter your date of birth.
Pick a boundary alert window, or keep 3 days.
Press Find zodiac sign.
Read your sign, its date range and the boundary check.
Scroll to the 12-sign table to compare elements and modalities.

Zodiac sign dates

These are the 12 date ranges the calculator uses. Both the first and last dates belong to the sign. Capricorn is the only one that crosses New Year.

Western zodiac sign dates used by this calculator
Sign	Dates	Element	Modality
Aries	March 21 to April 19	Fire	Cardinal
Taurus	April 20 to May 20	Earth	Fixed
Gemini	May 21 to June 20	Air	Mutable
Cancer	June 21 to July 22	Water	Cardinal
Leo	July 23 to August 22	Fire	Fixed
Virgo	August 23 to September 22	Earth	Mutable
Libra	September 23 to October 22	Air	Cardinal
Scorpio	October 23 to November 21	Water	Fixed
Sagittarius	November 22 to December 21	Fire	Mutable
Capricorn	December 22 to January 19	Earth	Cardinal
Aquarius	January 20 to February 18	Air	Fixed
Pisces	February 19 to March 20	Water	Mutable

Star sign by birthday: examples

Here's what the calculator returns for a few birthdays, with the default 3-day boundary alert.

Example results with a 3-day boundary alert
Birthday	Sign	Day in range	Boundary check
January 15	Capricorn	Day 25 of 29	5 days before Aquarius, no alert
January 20	Aquarius	Day 1 of 30	On the Capricorn and Aquarius change date
June 19	Gemini	Day 30 of 31	2 days before Cancer, alert shown
October 20	Libra	Day 28 of 30	3 days before Scorpio, alert shown
December 10	Sagittarius	Day 19 of 30	12 days before Capricorn, no alert

Elements, modalities and rulers

Astrology sorts the 12 signs into four elements (Fire, Earth, Air and Water), with three signs each. It also sorts them into three modalities (Cardinal, Fixed and Mutable), with four signs each. Your result lists the other signs that share your element and modality.

You'll also see your sign's polarity, its opposite sign six places away, and its ruler. Where traditional and modern astrology differ, both are shown. Aquarius, for example, has Saturn as its traditional ruler and Uranus as its modern one.

Born on a cusp?

A cusp is the border between two signs. Birthday charts print one change date, but the real moment the Sun moves into a new sign shifts a little from year to year. So someone born on or right next to a change date can get different answers from different sites.

This calculator still gives one sign, using the fixed dates above, and flags dates near a border. It doesn't use birth time or place. If you want the exact answer for a cusp birthday, you'd need a full birth-chart tool that uses those details.

What this lookup doesn't cover

Your sun sign is one piece of astrology. Moon signs and rising signs need your birth time and place, and Chinese zodiac animals follow a separate year-based system. None of those come from this date-only tool.

Astronomy is a separate subject too. The International Astronomical Union notes that the Sun's path crosses 13 constellations, including Ophiuchus, and they're not evenly spaced. Astrology's 12 signs are a different system. Treat your result as a fun cultural reference, not a measure of personality or a prediction.

Sources

These sources explain the astronomy side: the ecliptic, constellations and how they differ from astrology.

NASA Space Place: what are constellations?Explains constellations and how astronomy differs from astrology.NASA: reference systems and the eclipticDescribes the ecliptic, the Sun's apparent yearly path.International Astronomical Union: FAQsCovers the 13 constellations on the ecliptic, including Ophiuchus.NASA: solar system symbolsHistory of the planetary and zodiac symbols.

FAQ

What zodiac sign is January 20?

Aquarius, in this calculator's dates. Capricorn ends January 19 and Aquarius starts January 20. Because it's a change date, the result flags it, and some charts put the switch a day later.

What sign is someone born February 29?

Pisces. Pisces runs from February 19 to March 20, so a leap-day birthday sits 10 days into the range. It's Pisces whether or not you celebrate on February 28 or March 1.

Why does another site give me a different sign?

It may use slightly different change dates, an exact birth time, or a sidereal zodiac. Results usually only disagree for birthdays within a day or two of a sign change.

Can I have two zodiac signs?

Not as a sun sign. A cusp birthday sits near the border, but the Sun is in one sign at any moment. Other placements in a full birth chart can be in other signs.

Does the year I was born change my zodiac sign?

Not in this fixed-date lookup. In a full birth chart, the exact change moment varies a little by year, which only matters for birthdays right on a cusp.

Is Ophiuchus the 13th zodiac sign?

Ophiuchus is one of 13 constellations the Sun's path crosses, according to the International Astronomical Union. Western astrology still uses 12 signs, so this calculator does too.

What is my opposite zodiac sign?

It's the sign six places away in the cycle. Capricorn's opposite is Cancer, Aquarius's is Leo and Libra's is Aries. Your result shows it next to your sign.