✧ Free Big Three Calculator: Sun, Moon & Rising
Umbriel's free Big Three calculator finds your Sun sign, Moon sign and rising sign, each with its exact degree, from your birth date, time and place.
Runs in your browser.
4420+ people cast their chart here in the last 30 days.
No account, no email. The reading opens with all three read together, not as a list, because how they combine is the part a sign-by-sign table cannot give you.
- What you'll needBirth date, time and place
- What you getYour Sun, Moon and rising signs with exact degrees, and a plain-language reading of how the three work together
- CostFree, no account required
What the Big Three are
The Big Three are the Sun, the Moon and the Ascendant. They earned the nickname because between them they cover the three questions people arrive with: what drives you, what you feel, and how you meet the world. The Sun is the sign horoscopes are written for; the Moon is the private one; the rising sign is the doorway everyone else comes through.
They also move at wildly different speeds, which is why all three are needed to tell one person from another. The Sun takes a month to cross a sign, the Moon two and a half days, the Ascendant about two hours. Everyone born in your birthday week shares your Sun. Almost nobody shares all three.
Two honest caveats. The rising sign needs an accurate birth time, without one you have a Big Two, and Umbriel will say so rather than guess. And three placements out of forty-odd is a headline, not a chart. The aspects between them, the houses they fall in and the planets they answer to are where a reading stops being generic. The Big Three is the doorway, not the building.
How Umbriel computes it
This tool gives the sign and degree of your Sun, your Moon and your Ascendant (rising sign). The Sun's longitude comes from a calculation that agrees with NASA/JPL Horizons to under 1 arcsecond from 1650 to 2050, and the Moon's from a truncated ELP-2000/82 series that agrees to within 0.27 arcminutes over 1600 to 2050. The Ascendant is calculated from your local sidereal time (birth moment plus your longitude), the obliquity of the ecliptic and your latitude, and it agrees with an independent implementation to under 0.5 arcminutes. Your birth time is converted to UTC through the IANA time-zone database, so historical daylight saving is applied. The Sun and Moon depend on the date and, for the Moon especially, on the time: the engine's own table has the Moon moving about 13 degrees a day, so a birth time several hours out can change its degree and, near a sign boundary, its sign. The Ascendant depends on time and place and sweeps through the zodiac fast because sidereal time advances 15 degrees an hour, so it is the placement most sensitive to a wrong time; with no birth time Umbriel does not calculate an Ascendant at all. Signs are tropical by default and sidereal if you choose that setting, which is a change of convention and not of accuracy, and the house system does not alter the Ascendant. The way the three combine in the reading is interpretation, not measurement.
What's in your result
- Your Sun, to the degreeThe sign and exact degree: worth seeing if you were born near a cusp, where the date alone can mislead.
- Your Moon, to the degreePlus the house it falls in and its phase at birth.
- Your rising sign, to the degreeThe Ascendant, with the Midheaven and the house framework that follows from it.
- How the three read togetherUmbriel's reading opens with the three as one picture, where they agree, and where they pull against each other.
- The houses they land inSun and Moon by house, which is often the part people recognise faster than the signs.
- A clear answer if the time is unknownSun and Moon still stand; the Ascendant is left blank, not filled in with noon.
Don’t know your birth time?
Know it roughly? Give the time and say where it came from (a certificate, a parent’s memory, or something rough like “early morning”), and your chart tells you what could change within that window.
Don’t know it at all? Umbriel does not fill the gap with a guess. Tick “I don’t know the time at all” and it checks your whole birthday, hour by hour, then tells you two things: which placements are the same whatever time you were born, as exact as they would be if you knew the minute, and which are down to two signs, both named, so you know what a parent’s memory would settle.
The Ascendant, the Midheaven and the houses are left out rather than approximated. A birth time is the one thing they cannot be computed without, and an approximate Rising sign that looks exact is worse than no Rising sign at all.
What this calculator answers
The sign and degree of your Sun, your Moon and your Ascendant (rising sign).
How it calculates
The Sun comes from a solar-longitude calculation and the Moon from a shortened ELP-2000/82 series. The Ascendant comes from your local sidereal time, your latitude and the tilt of the Earth's axis. Your birth time is converted to UTC through the time-zone database. Signs are tropical unless you chose sidereal.
When the result is uncertain
The Ascendant is the most sensitive to a wrong birth time, because it sweeps the whole zodiac in a day; with no birth time Umbriel gives none. The Moon can change sign if the time is hours out. How the three combine in a reading is interpretation, not measurement.
Common questions
What are the Big Three in astrology?
Your Sun sign, Moon sign and rising sign. The Sun is traditionally read for drive and identity, the Moon for emotional life, and the rising sign for approach and first impression: three different questions rather than three versions of the same one.
Do I need my birth time for my Big Three?
For two of the three, no. The Sun and Moon can be worked out from the date alone in almost every case. The rising sign cannot. It changes roughly every two hours, so without a time there is nothing to calculate. Umbriel shows the two it can work out and leaves the rising sign open until you have a time.
Which of the Big Three matters most?
There is no settled answer, and anyone who gives you one is stating a preference. Modern popular astrology leans on the Sun, traditional astrology leans on the Ascendant and its ruler, and a great many people find the Moon describes them best. Reading all three against each other is more useful than ranking them.
Why is my Big Three different on another site?
Almost always the birth time zone. It has to be the zone of the birth city on the birth date, with the daylight-saving rule of that year, which older tables often get wrong. A birth close to a sign change will also differ between sources. Umbriel takes the zone from the birth place, not from your device.
Is the Big Three calculator free?
Yes. All three signs with exact degrees, the houses, and the reading, with no account and no email.
What if I don’t know my birth time?
Umbriel checks your whole birthday hour by hour and separates what is certain from what is not. Placements that are the same whatever time you were born are shown as exact. Placements that changed sign during the day are shown as two named signs, so you know what a parent's memory would settle. The Ascendant, Midheaven and houses are left out rather than approximated. They cannot be computed without a time, and an approximate Rising sign that looks exact is worse than none.
Do I need an account or an email address?
No. There is no sign-up, no email capture and no free trial. Enter your details and the result is drawn in your own browser.
Go deeper
Every one of these is a page in its own right, written out one at a time.
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Umbriel offers every system here as a set of prompts to think with, never as a statement of fact about who you are. Take what's useful, leave the rest.