Mercury sign calculator: what is my Mercury sign?

Mercury is the planet of the mind: how you take in information, how you put it into words and how quickly you change your view. Astrology has tied it to speech, learning, writing, trade and short journeys since the Greeks gave the planet the name of the messenger god. Your Mercury sign is the sign it stood in at the moment you were born, and it colors the style of your thinking more than its content.

Mercury is the swiftest planet. It circles the Sun in 88 days and the zodiac in about a year, so it spends anything from two weeks to nearly two months in a sign, depending on whether a retrograde loop falls on the border. That makes your exact birth date matter more here than it does for Jupiter or Saturn.

Seen from Earth, Mercury never gets far from the Sun. Its greatest distance is about 28 degrees, less than the 30 degrees of one sign. So your Mercury is always in your Sun sign or in the sign right before or after it. With the Sun in Gemini, Mercury can only be in Taurus, Gemini or Cancer. Venus follows the same rule with a wider leash of up to about 48 degrees.

A Mercury in the neighboring sign is common and entirely normal, and it is the reason two people with the same Sun sign can think and talk quite differently.

Mercury turns retrograde three or four times a year, for about three weeks each time, so roughly one person in five is born with Mercury retrograde. Seen from Earth it seems to move backward through the zodiac while our planet overtakes it, as the retrograde entry explains. The calculator marks it with ℞ whenever Mercury was moving backward on your birth date.

Astrologers read a natal retrograde Mercury as a mind that turns things over before it speaks: re-reading, revising and arriving at an answer by its own route. It describes a style of thinking, and the sign still sets its tone. To see the next retrograde and the sign it falls in, open the Mercury retrograde calendar.

In the traditional scheme Mercury rules Gemini and Virgo and is exalted in Virgo. In those signs it works at full strength: Gemini gives it speed and range, Virgo gives it precision. It is in detriment in Sagittarius and Pisces, the signs opposite, where thinking turns to the big picture or to impressions and detail slips. These words describe a tone; they say nothing about how intelligent anyone is.

The element shapes the style as well. Mercury in a fire sign speaks first and decides fast, in an earth sign checks and builds, in an air sign connects and compares, and in a water sign listens to mood and reads between the lines. The short readings above give the flavor of each sign.

With a birth time and place the calculator gives the house Mercury was in, Placidus by default, or whole sign, Koch and equal houses on the switch. The house names the area of life where the thinking goes: Mercury in the second house tends to talk about money, in the sixth about work and routine, in the tenth about career and public speech. Without a time the house stays open.

Because Mercury stays within 28 degrees of the Sun, it is often conjunct it, and traditional astrologers call a Mercury very close to the Sun combust. The birth chart calculator shows Mercury with every aspect it makes.

Mercury's position comes from the VSOP87 planetary theory, corrected for the time light takes to reach Earth and for the nutation of Earth's axis, which gives the apparent longitude astrologers use. In our checks it agrees with NASA JPL Horizons to within about one arcsecond on test dates between 1923 and 2077. The tool covers 1900 to 2099.

Mercury moves one to two degrees in a day, so a birth near the end of a sign can fall on either side of the line. When Mercury changed sign on your birthday, the calculator shows both signs and the time of the changeover; with a birth time it names the right one.

Your birth date and birthplace are enough for the sign. The birth time adds the house and settles the sign on the few days Mercury crossed a border. The tool is free and needs no account.

From here, the birth chart calculator draws Mercury among your other planets, Venus is the other planet that always stays close to the Sun, and the Mercury retrograde calendar lists the retrogrades ahead.