Planetary Bounds (Terms) in Astrology: The Hidden Rulers Within Each Sign

Each of the twelve zodiac signs is divided into five segments of unequal length, and each segment is ruled by one of the five non-luminary traditional planets. These segments are the bounds (also called terms, from the Latin terminus). If Mercury occupies 7 degrees of Aries, you look up which planet rules the bounds at that degree, and that planet is Mercury's bounds lord.

Bounds are one of the three minor dignities in the essential dignity system. When a planet sits in its own bounds (meaning it is the bounds lord at the degree it occupies), it gains +2 points. This is less than triplicity (+3) but more than face/decan (+1).

The Egyptian bounds table is the most widely used version and the default in Hellenistic practice. Its origin is attributed to an Egyptian source by Ptolemy, though the exact provenance is debated. The table assigns each segment a planet and a degree range that varies by sign.

For example, in Aries: Jupiter rules 0 to 6 degrees, Venus rules 6 to 12, Mercury rules 12 to 20, Mars rules 20 to 25, and Saturn rules 25 to 30. Each sign has a different distribution. The full table has 60 entries (12 signs times 5 segments).

Aries: Jupiter 0 to 6, Venus 6 to 12, Mercury 12 to 20, Mars 20 to 25, Saturn 25 to 30. Taurus: Venus 0 to 8, Mercury 8 to 14, Jupiter 14 to 22, Saturn 22 to 27, Mars 27 to 30. Gemini: Mercury 0 to 6, Jupiter 6 to 12, Venus 12 to 17, Mars 17 to 24, Saturn 24 to 30. Cancer: Mars 0 to 7, Venus 7 to 13, Mercury 13 to 19, Jupiter 19 to 26, Saturn 26 to 30. Leo: Jupiter 0 to 6, Venus 6 to 11, Saturn 11 to 18, Mercury 18 to 24, Mars 24 to 30. Virgo: Mercury 0 to 7, Venus 7 to 17, Jupiter 17 to 21, Mars 21 to 28, Saturn 28 to 30. Libra: Saturn 0 to 6, Mercury 6 to 14, Jupiter 14 to 21, Venus 21 to 28, Mars 28 to 30. Scorpio: Mars 0 to 7, Venus 7 to 11, Mercury 11 to 19, Jupiter 19 to 24, Saturn 24 to 30. Sagittarius: Jupiter 0 to 12, Venus 12 to 17, Mercury 17 to 21, Saturn 21 to 26, Mars 26 to 30. Capricorn: Mercury 0 to 7, Jupiter 7 to 14, Venus 14 to 22, Saturn 22 to 26, Mars 26 to 30. Aquarius: Mercury 0 to 7, Venus 7 to 13, Jupiter 13 to 20, Mars 20 to 25, Saturn 25 to 30. Pisces: Venus 0 to 12, Jupiter 12 to 16, Mercury 16 to 19, Mars 19 to 28, Saturn 28 to 30.

In most natal chart readings, bounds serve as a tiebreaker between planets with similar essential dignity scores. Where bounds become critical is in horary astrology and in timing techniques like distributions through the bounds (a Hellenistic predictive method). The bounds lord of the Moon in a horary chart is sometimes more important than the Moon's sign ruler.

Ptolemy proposed an alternative bounds table that he claimed was more rational, based on each planet's dignities and debilities in the sign. The Ptolemaic table differs from the Egyptian table in several signs but follows the same structural principle: five segments per sign, five non-luminary rulers.

In practice, the Egyptian bounds are used far more commonly. Most traditional astrology software and this calculator default to Egyptian bounds, with the Ptolemaic variant available as an option.

In the dignity scoring system, bounds contribute +2 when the planet is its own bounds lord and 0 otherwise (they never subtract). Because the scoring engine uses separate positive and negative branches, a planet in detriment or fall that holds bounds lordship scores +2, not -3. The positive bounds dignity causes the negative branch to be discarded entirely. Any positive dignity, including bounds alone, overrides all negative dignity.

Medieval astrologers gave bounds more interpretive weight than modern practice typically does. The bounds lord was considered a co-significator of the planet's condition, influencing how its significations manifest. Bonatti and Lilly both discuss bounds extensively in their delineation methods.