On this page
A birth chart (also called a natal chart) is a snapshot of where the Sun, Moon, and planets were positioned at the moment you were born, mapped against the twelve zodiac signs. This calculator computes your Big Three, Sun, Moon, and Rising, plus your Jupiter sign, element distribution (Fire / Earth / Air / Water), modality distribution (Cardinal / Fixed / Mutable), and your personal-planet placements (Mercury, Venus, Mars).
Enter your birth date, time, and city. Everything is computed in your browser in real time, your birth data is never stored on our servers, and the result URL is the only place it lives (yours to share or keep private).
What the Big Three actually mean
- Your Sun sign is the headline, it's the sign people mean when they ask "what's your sign?" It represents your core self, the energy you radiate through your day-to-day choices and how you most naturally show up.
- Your Moon sign is your inner emotional world: what soothes you, what makes you feel safe, how you process feelings privately. It's often very different from your Sun sign, which is part of why "I'm a Sagittarius but I don't feel like one" is so common, your Moon may be telling a different story than your headline.
- Your Rising sign (also called the Ascendant) is the sign that was rising on the eastern horizon at the moment you were born. It governs how strangers first perceive you, your "front door." Because the rising sign changes every two hours, it requires an accurate birth time; without one, we'll skip it.
Why we also show Jupiter and your element mix
Beyond the Big Three, two of the most useful additions for everyday self-reflection are:
- Jupiter sign, Jupiter is associated with growth, optimism, and luck. Its sign in your chart hints at the areas of life where things tend to come more easily, and where you grow through expansion.
- Element + modality distributions, counting the elements (Fire / Earth / Air / Water) and modalities (Cardinal / Fixed / Mutable) across all six placements gives you a chart "shape" that's often more telling than any single placement. A heavy-Air, heavy-Mutable chart processes the world very differently than a heavy-Earth, heavy-Fixed one.
How accurate is this?
The planet positions come from the open-source Astronomy Engine library, which is accurate to better than 1 arc-minute over the next century, far more than the 30°-per-sign granularity this calculator displays. The Rising sign uses the standard astrological formula (Right Ascension of MC + obliquity of ecliptic
- geographic latitude). Coordinates and historical timezones come from Geoapify, so the UTC offset for any past date (including DST rule changes) is handled correctly.
Source: Astronomy Engine (geocentric ephemeris) + standard ascendant formula
Examples
Born September 5, 1985 in Cleveland, Ohio
- Birth date 1985-09-05
- Birth time 14:30
- Birth location Cleveland, Ohio, United States
A late-summer Cleveland birth at 2:30 PM EDT yields a Virgo Sun (precise, observant, helpful), with the Moon and Rising depending on the exact minute. This time falls during EDT (Eastern Daylight Time, UTC-4), which the calculator handles automatically via the IANA timezone database (no need to remember whether DST was in effect).
Born July 14, 1992 in Tokyo, Japan, time unknown
- Birth date 1992-07-14
- Birth time
- Birth location Tokyo, Japan
With no birth time, we toggle "I don't know my exact time," and the calculator skips the Rising sign while still computing a confident Cancer Sun (born July 14 falls solidly within the Cancer Sun period from approximately June 21 to July 22). The Moon sign is shown but flagged with light uncertainty, for July 14, 1992 specifically, the Moon shifted from Sagittarius to Capricorn during the day, so the result depends on whether you were born in the morning or evening.
Frequently asked questions
What's the difference between a birth chart and a horoscope?
A birth chart is a fixed snapshot of where every planet was at the moment of your birth, it doesn't change over your lifetime. A horoscope is a transit-based reading: where the planets are right now relative to your fixed birth chart. Daily horoscopes are usually based on Sun-sign generalizations, which is why two people with the same Sun sign but different Moon and Rising can experience the same horoscope completely differently.
I don't know my birth time. Can I still use this?
Yes, toggle "I don't know my exact time." Your Sun sign will still be accurate (the Sun moves only ~1° per day, so date alone is enough). Your Moon sign may be off by one sign at the boundaries (the Moon shifts ~13° per day, crossing signs every ~2.5 days, so birth times near the boundary moments matter). Your Rising sign isn't computable without a time and we'll skip it. The personal planets (Mercury, Venus, Mars) and Jupiter are essentially unaffected for any time during the day, those planets move slowly enough that the date alone is sufficient.
What's the Rising sign and why does it need such precise time?
The Rising sign, formally the Ascendant, is the ecliptic point on the eastern horizon at the moment of your birth. Because the Earth rotates once per day, the entire 360° ecliptic rises once per day, so a new sign rises roughly every two hours. That means even a 30-minute uncertainty in your birth time can change which sign was actually rising. If your birth certificate has a recorded time, that's the most reliable source.
Does birth city really matter, or is just the country enough?
For Sun, Moon, and the planet placements, no, the city doesn't materially affect them, just the timezone (so the UTC moment of your birth is correct). For the Rising sign, however, the latitude matters: at very high latitudes (above ~65°), the Ascendant calculation produces unstable results because the ecliptic can become nearly tangent to the horizon. For most birthplaces, city precision is more than enough.
Why do you show Jupiter but not Saturn or the outer planets?
Jupiter is highlighted because it's traditionally the planet most associated with personal-scale luck and growth, it makes a satisfying addition to the Big Three for an everyday-self-reflection chart. The outer planets (Saturn, Uranus, Neptune, Pluto) are also meaningful, but they move so slowly that everyone born within a 2-3 year window has them in the same sign, which makes them more about generational character than personal personality. We may add them as an "advanced" expansion in a future update.
Does this calculator do houses, aspects, or transits?
Houses, yes (when your birth time is known). We use the whole-sign house system: the simplest and arguably oldest, where the rising sign IS the 1st house, the next sign is the 2nd, and so on around the wheel. The results page includes a 12-row table showing which sign sits on each house and which planets fall in each. We don't yet compute aspects (the angular relationships between planets) or transits (current planet positions relative to your chart). Those may come later.