The tool answers yes or no for the date you choose, gives the moments Mercury turns, the shadow either side, and, if you add your birth details, the houses of your chart the retrograde falls in and the planets Mercury passes over. Mercury turns retrograde three times in most years and four times in some: in the 175 years from 1900 to 2074 our data shows 149 years with three retrogrades and 26 with four. Each one lasts between about 20 and 24 days.
How it works
Mercury’s position comes from NASA JPL DE440 data in the tropical zodiac, the one Western astrology uses. The moments Mercury stands still and turns, called the stations, were found when the data files were built, from the change in the direction of its motion. Between the two stations Mercury is retrograde.
The shadow is a modern convention, and we know of no classical source for it. The tool follows the definition most often given, as set out on our Mercury retrograde explainer. The pre-shadow begins when Mercury first reaches the degree where it will later turn direct. The post-shadow ends when it comes back to the degree where it turned retrograde. The tool finds both moments by searching Mercury’s position to the second. The stretch of the zodiac between the two station degrees is the retrograde zone, which Mercury crosses three times: forward in the pre-shadow, backward while retrograde and forward again in the post-shadow.
With a birth time, the tool casts your houses for your birth moment and place, in the Placidus system or Whole Sign houses, and lays the retrograde zone over them. Any planet of yours inside the zone is listed with the dates Mercury passes it.
Reading the result
The first line answers the question. Retrograde means Mercury is moving backward against the stars on that date. Pre-shadow and post-shadow mean it is moving forward but inside the zone it will cover, or has just covered, while retrograde. Direct means it is outside all of that, and the tool shows when the next retrograde begins.
The table gives the four moments of the cycle in your device’s time zone and in UTC, with the degree Mercury stands at. The house lines say which parts of your chart the retrograde passes through, using the same house themes as our other chart tools. Modern astrologers read those houses as the areas of life that invite a second look while Mercury is retrograde.
Where traditions differ
Not every astrologer uses the shadow. Some read only the retrograde weeks themselves; the tool shows both so you can choose. House systems also differ: Placidus is the default here, and Whole Sign houses are one tap away. Vedic astrology uses the sidereal zodiac, so Mercury’s sign is often different there, but the stations fall within a minute or two of the same moment in both systems: Mercury turns when it turns, whichever zodiac you measure it in.
What it does not do
It does not predict events, and it does not say a retrograde is good or bad for you. It covers Mercury only; for Venus and Mars see the Venus retrograde 2026 and Mars retrograde 2027 pages. Dates run from 1900 to 24 November 2074, the range our planet data covers with room for a whole cycle.
Frequently asked questions
↳ Is Mercury retrograde right now?
The tool answers that for today as soon as you press the button, with the time it turned and the time it turns back. In 2026 Mercury is retrograde from 26 February to 20 March, from 29 June to 23 July and from 24 October to 13 November (UTC dates).
↳ What are the pre-shadow and the post-shadow?
They are the weeks before and after a retrograde when Mercury moves forward through the same degrees it covers while retrograde. The pre-shadow starts when Mercury first reaches the degree where it will turn direct, and the post-shadow ends when it gets back to the degree where it turned retrograde.
↳ Do I need my birth time?
Not for the yes or no answer, the dates or the shadow. Houses need a birth time, because they change every few minutes. Without a time the tool still lists which of your planets, other than the Moon, sit inside the retrograde zone.
↳ Why does Mercury seem to move backwards?
Mercury orbits the Sun faster than Earth does. When it passes between Earth and the Sun, its movement seen from Earth runs backward against the stars for a few weeks. The planet itself never changes direction.
↳ Are the dates the same in Vedic astrology?
The moments are the same to within a minute or two, because a station is a real change in Mercury's apparent motion. The sign is often different, because the Vedic zodiac is measured from the stars and sits about 24 degrees behind the Western one.
↳ Does Mercury retrograde really cause problems?
There is no scientific evidence that it does. Many people use it as a reminder to slow down, back things up and read twice before sending, which is useful in any month.