☾ Free Moon Sign Compatibility Calculator
Umbriel's free Moon compatibility calculator compares two Moons — their signs, exact degrees, the aspect between them and where each falls in the other's chart. No account, no email. It works from the real positions rather than from sign pairs, so a Moon at 1° and a Moon at 29° of the same sign are not treated as identical.
- What you'll needBoth people's birth dates (times for the houses)
- What you getBoth Moons with exact degrees, the aspect between them, and where each Moon falls in the other's chart
- CostFree — no account required
Runs in your browser. Nothing to install, nothing to set up.
What Moon compatibility actually is
Of all the comparisons people make between two charts, the Moon is the one most astrologers would keep if they could only keep one. The Sun describes what someone is aiming at; the Moon describes what they need in order to be comfortable — sleep, food, mess, quiet, reassurance, the shape of an ordinary evening. Two people can admire each other's Suns and still find the daily rhythm hard, and that is usually a Moon conversation.
⚠️ Sign-pair compatibility tables are where this goes wrong. They treat every Cancer Moon as the same Cancer Moon, when what actually matters is the aspect between the two Moons and how tight it is. Two Moons in trine at half a degree behave like one instrument; the same trine at eight degrees is barely audible. And two Moons in the same sign at opposite ends of it are not conjunct at all.
The other half is placement. Where your Moon falls in their houses — and theirs in yours — describes the area of life each person's needs land in for the other. It is often more recognisable than the aspect, and it is the part that needs both birth times. Umbriel gives the degrees, the aspect with its orb and the overlays, and does not convert any of it into a percentage.
What's in your result
- Both Moons, to the degreeSign and exact degree for each, so near-cusp Moons are visible.
- The aspect between themNamed, with its exact orb — the number that decides how loud it is.
- Each Moon in the other's housesWhere each person's needs show up for the other. Needs both birth times.
- Moon phase and elementEach Moon's phase at birth and the element pairing, as a lighter second reading.
- Moon to the other's Sun, Venus and SaturnThe contacts that most often describe how the two settle together.
- The full synastry alongsideThe Moon comparison sits inside the complete chart comparison if you want the rest.
Common questions
What is Moon sign compatibility?
Comparing the Moon in two birth charts — the aspect between them and where each falls in the other's chart. The Moon is traditionally read for emotional needs and daily rhythm, which is why it is often considered the most telling single comparison.
Are the same Moon signs the most compatible?
Not automatically. Two Moons in the same sign are only conjunct if they are close in degree — one at 2° and one at 27° of the same sign are almost thirty degrees apart. Sameness is also not the only thing that works; complementary Moons often describe an easier daily life than identical ones.
Do we both need birth times?
For the Moon signs and the aspect between them, usually not — though a Moon can change sign within a day, so a birth close to an ingress does need a time. For the house overlays, yes, both times.
Is the Moon more important than the Sun for compatibility?
Many astrologers think so, and the reasoning is practical rather than mystical: the Sun describes what someone is reaching for, the Moon what they need to be comfortable, and living together is mostly the second thing. It is a view worth testing against your own experience rather than accepting.
Is the Moon compatibility calculator free?
Yes — both Moons, the aspect with its orb, and the overlays, with no account and no email.
Go deeper
Every one of these is a page in its own right, written out one at a time.
Related free tools
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.