What your Mars sign is
Mars is the planet of drive, action and assertion. In modern astrology the sign Mars occupied when you were born is read as the way you go after what you want: how you start things, how you compete, how you handle anger and how you express desire. Where the Sun sign is often described as who you are and the Moon sign as how you feel, the Mars sign is described as how you act on both. It is one of the personal planets in a chart, along with Mercury and Venus.
How long Mars stays in a sign
Mars takes about 687 days to circle the zodiac, so on average it spends around eight weeks in each sign. Its pace varies a great deal: when it appears to turn back it can linger in one sign for several months, and at other times it crosses a sign in a few weeks. This means that, unlike the Moon, Mars has the same sign for many people born in the same stretch of weeks, and your Mars sign can match your Sun sign, or sit anywhere around the wheel. Mars can be in any sign relative to the Sun, because it travels beyond Earth’s orbit.
How the tool finds it
Your local birth time is converted to universal time using the time zone that applied at your birthplace on that date, with daylight saving. The position of Mars at that moment is then read from Swiss Ephemeris samples and interpolated between them, accurate to a couple of arcseconds. That position is an ecliptic longitude measured from the March equinox. Each sign is thirty degrees wide, so the tool divides by thirty for the sign and shows the remainder as degrees and minutes within it. The method is the tropical zodiac of Western astrology.
If Mars is within one degree of the end of a sign, the tool warns you, because a different clock time or place could put it on the other side of the line. The tool also shows whether Mars was direct or retrograde.
No birth time
Mars moves at most about three-quarters of a degree a day, so it rarely changes sign on any given day. If you leave the time blank, the tool works from the whole of the date. On the occasional day when Mars changes sign, you see both signs and the time of the change in your local clock, which is enough to decide which applies if you know whether you were born before or after.
Mars retrograde
Roughly every two years, for about two months, Mars seems to move backwards against the stars as Earth overtakes it. A retrograde Mars is read by some astrologers as drive that turns inward or builds slowly before acting, and others give it no special weight. It is an interpretation and not a prediction, and it says nothing about courage or ability. If you were born during one of these periods, the tool tells you.
Reading the description kindly
The descriptions in the tool come from the long tradition of modern astrology, and they describe tendencies in a style of acting, not fixed traits. Someone with Mars in Pisces can be decisive, and someone with Mars in Aries can be patient. In traditional astrology Mars is called strong in Aries, Scorpio and Capricorn, the sign of its exaltation, and weaker in Libra, Taurus and Cancer; the tool mentions the exaltation where it applies, and modern writers often treat such labels as shorthand rather than a judgement. For more about the signs, see the astrology guides, and for the rest of your chart, try the Sun, Moon and Rising calculator. The Venus sign calculator and Mercury sign calculator cover the other two personal planets.
Frequently asked questions
↳ What does my Mars sign say about me?
In modern astrology it describes your style of taking action: how you begin things, compete, and handle anger and desire. It is a tendency described by a tradition, not a measured trait, and it sits alongside the rest of your chart.
↳ How often does Mars change sign?
About every eight weeks on average, but it can stay in one sign for several months when it slows and turns retrograde, and it crosses a sign in a few weeks at other times. The tool shows the exact sign for your date.
↳ Can my Mars sign be different from my Sun sign?
Yes, and it often is. Mars can be in any sign relative to the Sun, because its orbit lies outside the Earth's, unlike Venus and Mercury, which stay close to the Sun.
↳ Is a retrograde Mars a bad sign?
No. A retrograde planet only appears to move backwards as seen from Earth. Some astrologers read it as inward or slow-building drive, and others ignore it. It is not a prediction or a flaw.
↳ Why does the tool ask for my place of birth?
To work out the right time zone, including daylight saving, so your clock time becomes the correct universal time. The place is used in your browser only and is not sent to us.