What this calculator tells you
Your Mercury sign is the sign containing Mercury’s geocentric longitude at birth. This calculator returns its degree, house and direct or retrograde motion as well. The sign is calculated independently of your Sun sign, even though Mercury appears comparatively close to the Sun.
Mercury’s sign and motion are separate results
The sign is a location along the zodiac. Retrograde means the calculated ecliptic longitude was decreasing with time; direct means it was increasing. Mercury can occupy the same sign during both types of motion. The result therefore labels motion separately from the sign.
The signed speed is shown in degrees per day. A negative value indicates retrograde longitude motion in this model. That is an apparent geocentric motion, not Mercury physically reversing its orbit around the Sun.
Find Mercury’s chart context
The house number places Mercury inside the selected house division. To inspect its connections, open the complete chart and select Mercury or an aspect involving Mercury. The chart displays only relationships inside the selected aspect types and orbs.
In traditional symbolic interpretation Mercury is associated with communication, exchange and reasoning. The calculator itself reports positions; it does not assess your intelligence or determine how you must communicate. Keep symbolic discussion separate from the measured longitude.
A CONCRETE EXAMPLE
Mercury in the fixed Greenwich example
The stored example places Mercury at 1°53′ Capricorn in House 9, while the Sun is also in Capricorn but in House 10. Sharing a sign does not require two planets to share a house: an unequal-house cusp can fall inside that sign.
This preserved, fictional example uses 1 January 2000, 12:00 UTC, Greenwich (51.4779° N, 0°), tropical zodiac and Alcabitius houses. Its stored source is Swiss Ephemeris 2.10.03. New calculations use Skyfield + JPL DE440; the historical example is not relabelled as a new calculation.
Read it in your own chart.
Keep the date, recorded time, location and zodiac visible as you compare results. Guest calculations need no account.
Use the calculator aboveCommon questions
Is Mercury always in the same sign as the Sun?
No. Mercury stays relatively near the Sun as seen from Earth, but a zodiac boundary can lie between their longitudes. Read the calculated Mercury position instead of copying the Sun sign.
Can this tell whether Mercury was retrograde at birth?
Yes. The result reports the stored longitude speed and direct or retrograde state for the submitted birth instant. It does not search for the exact beginning or end of that retrograde period.
Does Mercury retrograde change its sign?
Not by definition. Retrograde describes decreasing longitude; the sign changes only if the position crosses a sign boundary. Sign and motion are displayed separately.
Calculation & interpretation
New personal calculations use Skyfield with JPL DE440 data and the site’s documented house and zodiac rules. The preserved Greenwich teaching chart has its own historical source label. Worked arithmetic and geometry examples are labelled separately. Astrological meanings are symbolic conventions, not established scientific predictions.
Birth time and place affect angles and houses. Unsupported or ambiguous inputs return an error rather than an invented chart. Personal results stay in browser state and do not create public result URLs.
- Skyfield: positions and coordinates
- NASA/JPL: planetary and lunar ephemerides
- IANA: time zone database