A date is a day. A sign change is a moment.
Sun sign cusp calculator
Born near the boundary between two zodiac signs? Check what the Sun actually did on your birth day—not what a fixed date list says.
Your Sun occupies one sign at the moment of birth. If it changed signs that day and your time is unknown, there may be two possible answers. That is missing information, not a two-sign personality.
Check my birth dayCancer → Leo is an illustration, not your result.
Check your Sun sign boundary
Start without a birth time. We’ll check whether the Sun changed signs on that date, in that city’s timezone.
The method
How the cusp check works
Use the real year and local date
The Sun does not enter a sign at the same clock time every year. Familiar date ranges are a guide, not a calculation for your birth.
Resolve the city’s timezone
The Sun’s crossing is one moment worldwide, but the local clock and sometimes the calendar date differ. Birth city coordinates select an IANA timezone.
Compare the start and end of the day
Lunara’s existing Swiss Ephemeris calculator checks the Sun’s geocentric tropical longitude at local midnight and just before the next midnight. If the signs differ, it narrows the crossing to about one minute.
What your result tells you
Same sign all day: your date is enough to identify the Sun sign, provided the date and timezone are correct. The exact degree still depends on the time.
A sign change that day: compare a reliable birth time, or a known morning/evening window, with the displayed crossing. If your window overlaps it, the sign remains uncertain.
This tool uses the tropical zodiac. It is not a sidereal Sun-sign calculator, a full natal chart or birth-time rectification.
A sourced boundary-day example
July 22, 1992.
Cancer or Leo?
Selena Gomez · Grand Prairie, Texas
Our sourced Selena Gomez and Benny Blanco chart comparison places the Cancer-to-Leo crossing at approximately 09:09 a.m. CDT on Selena’s local birth date.
The article cites a published 7:19 a.m. birth time whose source labels it C: accuracy in question. If that time is correct, it falls before the crossing. If it cannot be trusted, the date alone leaves Cancer or Leo possible. We do not use the questionable time to declare her Sun sign settled.
Try July 22, 1992 and select Grand Prairie, Texas in the finder. This illustrates why the year, place and reliability of a birth time matter—not why anyone “acts like” one sign.
Does being on a cusp mean two Sun signs?
Not in this calculation. The tropical zodiac divides longitude into twelve separate signs; the Sun’s position belongs to one at a given instant. “Cusp” is a useful everyday word for a boundary birthday, not a third or blended sign.
Can my personality settle the answer?
No. Relating to a description cannot establish a birth time or choose a side of an astronomical boundary. Start with a birth certificate, hospital record or family record. Keep an uncertain time uncertain.
How certain is the displayed minute?
It is approximate. We bracket the crossing to about one minute, not an exact second. Historical timezone records, daylight-saving rules and political boundaries can be imperfect; some clock changes even repeat or skip local times or dates.
Use the Gregorian local date recorded where you were born, including any needed calendar conversion. A wrong city, date or uncertain recorded time can change a boundary-day answer. Early dates and times close to the crossing deserve a careful check of the original record and local clock rules.
We support dates from 1900 onwards. City selection helps resolve the timezone; it does not certify historical birth data.
Your Sun is the starting point.
Explore the rest of your chart with the same care. Enter a recorded time if you know it; leave it unknown if you don’t. Rising signs and houses need a reliable birth time.
Free chart first. Paid report optional.