What this calculator tells you
Your Moon sign is the zodiac sign containing the Moon’s calculated geocentric longitude at birth. The Moon moves quickly enough for birth time to matter near a sign boundary. Enter the local birth time and time zone to calculate a position rather than relying on a date-only table.
Check the instant before comparing Moon signs
A local date and time must be converted to a specific instant. Two people using noon in different time zones are usually comparing different instants. The result shows the UTC timestamp so you can check that detail when two websites disagree.
These are geocentric positions, measured from Earth’s centre. Birthplace affects time resolution and houses; it does not turn the Moon calculation into a topocentric position measured from your surface location. Compare like conventions, especially for the nearby Moon.
Separate Moon sign from Moon house
The sign follows the Moon’s longitude in the selected zodiac. Its house follows the entered time, place and house system. Changing a house system may change the house number while leaving the Moon’s zodiac position unchanged.
If your birth time is uncertain, calculate the earliest and latest plausible times. Matching signs at those endpoints is a useful first check; a result near a boundary needs closer attention. This tool does not automatically search the exact time the Moon changes signs.
A CONCRETE EXAMPLE
Moon in the fixed Greenwich example
The preserved Moon position is 13°19′ Scorpio in House 7. Its longitude, 223.32379971°, is 13.32379971° beyond the 210° start of Scorpio. The sign and house answer different questions: where along the zodiac, and where within the chosen local house division.
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
Can my Moon sign differ from my Sun sign?
Yes. The Sun and Moon have different geocentric longitudes. Calculate Sun, Moon and Rising together to see the separate positions instead of inferring one from another.
Why does another calculator give a different Moon sign?
First match the local date, time zone and UTC instant. Then match tropical or sidereal zodiac, ayanamsa and geocentric or topocentric convention. Near a boundary, small time differences can also matter.
Does this calculate Moon phases or lunar returns?
No. This page gives a birth Moon position and house. It does not search for a lunar return or report the exact time of a phase.
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