What is my Mercury sign?

What a Mercury sign is

It is the zodiac sign Mercury occupied at the moment you were born, which in plain terms is an angle: the zodiac is the ecliptic circle, the track Earth's orbit traces on the sky, divided into twelve arcs of 30 degrees, and Mercury is somewhere along it at every moment. The planet stays in one sign for about three and a half weeks on average (often under three), and for up to about ten weeks when a whole retrograde loop fits inside one sign. That is why the date is usually enough here, while the Moon needs the hour far more often. What astrologers make of the placement lives in the twelve portraits further down; this calculator only tells you which one is yours.

Mercury is never far from your Sun

This is astronomy, not interpretation. Mercury orbits closer to the Sun than we do, so from Earth it never appears more than about 28 degrees away from it, which is less than the 30 degrees of one sign. Checking every day from 1900 to 2100, the whole range this tool covers, Mercury's sign is your Sun sign or one of the two immediately beside it, without a single exception. So if a calculator hands you a Mercury three or four signs away from your Sun, the mistake is in the calculator. It also means Mercury and the Sun share a sign about half the time, which is ordinary rather than special.

Find your Sun sign first →

Born on a day Mercury changed sign

Mercury changes sign on 4.05% of days, so roughly 1 birth date in 25 straddles a boundary. On such a date many calculators quietly assume an hour, usually noon or midnight in some timezone, and hand you one sign with full confidence. We show both, plus the exact minute of the change in the timezone you selected, so you can settle it yourself if you know even roughly when you were born. On the other 24 days out of 25 there is nothing to guess: Mercury holds the same sign at both ends of your day and moves one way between them, so no birth hour inside it produces a different answer. There is exactly one exception in three centuries, 4 January 1970, when Mercury turned around right on the boundary and touched the neighbouring sign for a few hours; we flag that day separately.

Retrograde is a different question

Mercury is retrograde on 19.15% of days, about 1 day in 5, so a retrograde Mercury at birth is common rather than rare. Direction and sign are independent: Mercury can be retrograde in any sign, and being retrograde does not move it out of the sign it is in. We show the direction below your result as a secondary line, because the honest version of that question needs the birth hour on the 1.72% of days when Mercury turns around, and that is what the dedicated calculator is for.

Was Mercury retrograde when you were born? →

How we compute it

Mercury's position comes from the same ephemeris data professional astrology software relies on: an apparent geocentric longitude, which is why no birth city is needed. Signs are tropical, anchored to the March equinox rather than to the constellations, so a sidereal or Vedic calculator will usually show you the previous sign. Your day is the civil day in the timezone selected next to the time field, midnight to midnight. Without a birth time we compute for noon inside that day, and we also read Mercury at both of its ends: if the two ends sit in different signs, you get both candidates instead of a verdict, and the exact instant of the change, found by narrowing the interval until it stops moving. With a birth time we compute for that instant instead.

Mercury in every sign

Twelve portraits, one per sign. Read the one your Mercury falls in, then the one belonging to whoever you keep misunderstanding by email.

Mercury through all twelve signs →

The planet Mercury in astrology: the full guide →

Frequently asked questions