▼ Free Imum Coeli (IC) Calculator: Your IC Sign and Degree
Umbriel's free Imum Coeli (IC) calculator finds the sign and degree of your IC, the lowest point of your chart and the point opposite your Midheaven, from your birth date, exact time and place.
Free, no account, no email. Runs in your browser.
14160+ people cast their chart here in the last 30 days.
No account, no email. The IC is worked out from your birth moment and place.
TRADITIONALA traditional technique: in the books before 1700.
- What you'll needBirth date, exact time and place
- What you getYour IC sign and exact degree, your Midheaven opposite it, and the rest of your birth chart
- CostFree, no account required
What the Imum Coeli is
Imum Coeli is Latin for the lowest part of the sky, and astrologers shorten it to the IC. It is the point on the zodiac that was directly beneath your feet at birth, the exact opposite of your Midheaven. Together they are the vertical axis of the chart; the Ascendant and Descendant are the horizontal one.
Deeper.a one-breath read
The IC is one of the four angles, which the old books treat as the strongest places in a chart. By tradition it speaks for the roots: home, family, the ground you grew up on and the private self nobody is shown. In the quadrant house systems (Placidus, Koch, Regiomontanus and the like) it is also the start of the fourth house.
It moves about a degree every four minutes, passing through a whole sign in roughly two hours. That is why it needs your exact birth time: with no time at all, the date cannot say which sign it was.
How Umbriel computes it
Deeper.a one-breath read
Umbriel computes the Midheaven from the sidereal time at your birth place and moment, and your IC is that point plus 180°. The sidereal time is checked against the worked example in Jean Meeus's Astronomical Algorithms (10 April 1987, 19h21m UT: mean sidereal time 8h34m57.09s printed; Umbriel's apparent value is 8h34m56.8s, 0.2 seconds less, which is the nutation). Without a birth time, Umbriel leaves the IC out rather than approximating it, because an approximate angle that looks exact is worse than none.
What's in your result
Deeper.a one-breath read
- IC sign and degreeWhere your IC falls, to the arcminute, with a plain warning if it sits near a sign edge.
- The Midheaven opposite itThe top of the sky at your birth, the other end of the same axis.
- Why the time mattersHow many minutes of error would move the IC into the next sign.
- Rising and DescendantThe other axis, on the same page.
- Your whole chartThe Sun, Moon and houses, built from the same moment.
Don’t know your birth time?
Deeper.a cup-of-tea read
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.
Common questions
What does my IC sign mean?
The IC is read for roots, home, family and the private self. An IC in Cancer is often read as a pull toward a nourishing, sheltered base, an IC in Aquarius as a home life that is unconventional or full of friends. Best held as a question to think with, not a verdict on anyone's family.
How do I find my IC from my Midheaven?
Go to the opposite sign and keep the degree. A Midheaven at 9°58′ Gemini gives an IC at 9°58′ Sagittarius. Umbriel does it for you from your birth time and place.
Is the IC the same as the fourth house?
In the quadrant house systems (Placidus, Koch, Regiomontanus, Campanus and Porphyry) the IC is the cusp of the fourth house. In whole-sign and equal houses the fourth house starts at the sign or degree set by the Ascendant instead, so the IC can fall inside it.
Can I find my IC without a birth time?
No. It passes through a whole sign about every two hours, so the date alone cannot say. Umbriel leaves it out rather than guessing.
How accurate is the IC here?
As accurate as your birth time. The IC moves about a degree every four minutes, so a time that is out by eight minutes can move it about two degrees.
Is this IC calculator free?
Yes: sign, degree and the Midheaven opposite it, with no account and no email, calculated in your own browser.
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, not generated on the fly.
Related free tools
Next doorDescendant Sign CalculatorUmbriel's free Descendant calculator finds your Descendant, the cusp of your seventh house, with its sign and exact degree, from your birth date, exact time and place.Prints in the head of this page, all public domain except where stated: Astrological chart (?). Woodcut (?), Wellcome Collection; Urania's Mirror, Sidney Hall, 1825, Library of Congress via Wikimedia Commons; Johannes Hevelius, Machina coelestis, Danzig, 1673, Silesian Digital Library. Ground: Andreas Cellarius, Harmonia Macrocosmica, 1661, Wikimedia Commons.
Further down the page: Jupiter and Mercury in the House of Philemon and Baucis, Hendrick Goudt, 1612, Art Institute of Chicago. The next-door print comes from that page's own head. The pointing hand: a pointing hand, after a medieval manuscript margin (line art by Jerimee).
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.