Mars sign calculator: find your Mars sign

Mars is the planet of action. In a birth chart its sign describes the way you start things and push them through, what you do when someone blocks your path, how you compete and how you handle anger, your own and other people's. It also colors desire and physical energy, which is why astrologers look at Mars for sport, sex and the kind of work that leaves you tired but satisfied.

Where Venus describes what you are drawn to, Mars describes how you go after it. The two are read together in love, and a Mars sign that sits uneasily with your Sun sign often explains why your temper surprises people who know you mainly through your Sun.

Mercury and Venus orbit inside Earth's path and always stay close to the Sun, so their signs sit next to your Sun sign. Mars orbits outside it. Seen from Earth it can stand in any sign relative to the Sun, even directly opposite it, so your Mars sign can be any of the twelve whatever your birthday.

Mars is also uneven in speed. Our engine finds it spending a median of about six and a half weeks in a sign between 1900 and 2099, but a retrograde loop can hold it in one sign for up to about seven and a half months. That is why the calculator shows the date Mars entered your sign and the date it left: for some people that span covers most of a year.

Roughly every twenty six months Mars stops, turns back for about two and a half months and then resumes its course. Our engine finds Mars retrograde on about one day in ten, so about one person in ten is born with it. The calculator marks it beside the degree, and the retrograde planets calendar lists every Mars retrograde with its dates.

Astrologers read a natal Mars retrograde as drive that is worked out privately before it is shown: anger that is slow to surface and long to fade, effort that goes into rethinking and repairing rather than charging ahead, and a way of competing mostly with oneself. The retrograde glossary entry explains the geometry of the backward loop.

Mars enters a new sign on about one day in fifty, so a birth date usually settles the Mars sign without a time. When your birthday is one of those days and you leave the time out, the calculator shows both signs with the exact minute of the change in your birthplace's local time, including any summer time in force. With a time, it names the sign directly and warns you if your birth was within half an hour of the change, since recorded birth times are often rounded.

A time also gives the house of Mars in the Placidus system. The sign tells you how you act; the house tells you where you spend that energy, whether on your career, your home, your body or your friendships.

Mars is half of the classic pairing of attraction. When one person's Mars touches the other's Venus, astrology reads a spark that is easy to feel and hard to explain; when two Mars signs clash, arguments tend to follow the same script. Find both Mars signs here, then run the two charts through the compatibility calculator to see the actual aspects between them.

Our Venus sign calculator works the same way, so you can look up both planets for yourself and for a partner in a couple of minutes.

The position of Mars comes from the VSOP87 planetary theory with light time, aberration and nutation applied, giving its apparent place in the tropical zodiac used in Western astrology. Checked against the Swiss Ephemeris for fifteen dates from 1901 to 2099, it agrees to within a third of an arcsecond, and the retrograde flag matches the ephemeris' daily motion.

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