→ Free Primary Directions Calculator
Umbriel computes primary directions in mundo and in zodiaco, with latitude, for any significator — the oldest and most technically demanding predictive method in Western astrology. Free, in your browser, no account.
- What you'll needBirth date, time and place — an accurate time above all
- What you getDirections from any significator to any promissor, with dates, in mundo and in zodiaco
- CostFree — no account required
Runs in your browser. Nothing to install, nothing to set up.
What it actually is
Primary directions move the chart by the rotation of the Earth rather than by the motion of the planets. Roughly four minutes of rotation after birth stands for one year of life, which means the whole method rests on the diurnal turn — the same rotation that produces day and night.
It is the oldest predictive technique in the Western tradition and by a distance the most technically demanding. Ptolemy used it; so did every serious astrologer for the next fifteen centuries; and it fell out of use largely because doing it by hand is punishing.
⚠️ Four minutes of clock time is one year of life. That is the sentence to hold on to: a birth time out by fifteen minutes moves every direction in your life by nearly four years. No other technique is this unforgiving about the birth time, and a rectified time is standard practice before anyone reads directions seriously.
There is more than one convention — in mundo or in zodiaco, with or without latitude, and several competing keys for converting arc to time. Umbriel computes both frames and lets you choose the key rather than burying the choice.
How Umbriel computes it
Directions are computed in mundo as well as in zodiaco, and with the significator's own latitude taken into account rather than flattened to the ecliptic — which is the difference between a technique that agrees with itself and one that quietly does not. The implementation is checked by invariant rather than against a reference chart: two independent methods must agree on when a body reaches an angle, and that check is what caught a bug placing the Descendant at 310 degrees, which no published example chart would have revealed.
What's in your result
- Directions in mundo and in zodiacoBoth frames, since practitioners disagree about which is primary.
- Latitude taken into accountRather than flattening every body onto the ecliptic.
- Any significatorNot only the Ascendant and Midheaven — direct from any point you like.
- Converted to datesWith the key stated, since the choice of key changes every date.
- Ordered by yearSo the sequence of a life reads as a sequence.
Common questions
What are primary directions?
A predictive technique that moves the chart by the Earth's rotation rather than the planets' motion — about four minutes of rotation for each year of life. It is the oldest such method in Western astrology.
Why do primary directions need such an exact birth time?
Because four minutes of clock time equals a year. A birth time out by a quarter of an hour puts every direction almost four years wrong, which is enough to make the whole technique useless.
What is the difference between in mundo and in zodiaco?
In mundo directions work in the frame of the local horizon and meridian; in zodiaco directions work along the ecliptic. They give different dates, and astrologers disagree about which is correct. Umbriel computes both.
Which key should I use?
There are several — Ptolemy's, Naibod's, and others — and each converts arc to time slightly differently, so each gives different dates. There is no consensus. Umbriel names the key it is using rather than hiding the choice.
Is the primary directions calculator free?
Yes — both frames, any significator, with dates, and no account.
Go deeper
Each of these is a free tool in its own right.
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.