Mercury Sign Calculator

What Your Mercury Sign Describes

Mercury describes the mind at work: how you take in information, how you make sense of it and how you put it into words. A Gemini Mercury may think out loud and jump between ideas; a Capricorn Mercury may think in plans and say less, more carefully. Read more about Mercury in astrology.

How the Mercury Sign Is Calculated

Mercury never strays more than about 28 degrees from the Sun, so your Mercury sign is always your Sun sign or one of the two signs beside it. It usually crosses a sign in two to four weeks, about 27 days on average, but it turns retrograde three or four times a year, and a retrograde near a cusp can hold it in one sign for up to 69 days.

The calculator finds Mercury's apparent geocentric longitude at your birth instant and also tells you whether Mercury was retrograde when you were born.

Why Birth Time Matters

Between 1900 and 2060, Mercury changed sign on about 4% of days, roughly 1 day in 25. If your birthday is one of them, the sign depends on the hour you were born. Without a time, the calculator checks every hour of your birth date (in every time zone, if you leave out the place) and shows each sign Mercury could have held.

With your birth time and place, the result also gives the exact degree and the house, the area of life where this placement works.

How Accurate Is It?

Positions come from Selfgazer's astrology engine, the same one that draws the chart in your astro room: VSOP87 planetary theory through Astronomy Engine, with Chiron from Swiss Ephemeris tables. Tested against the Swiss Ephemeris, planets agree to within half an arcminute and house cusps to within a tenth of an arcminute. Your local birth time is converted with your birthplace's historical time zone rules, including past daylight saving changes. Everything is calculated in your browser, and nothing you enter is stored.