How we score compatibility

Every compatibility score on VenusBond comes from one formula, applied the same way to every pair of signs. This page gives all of it: the inputs, the weights and a worked example. The tables below are drawn from the same code that produces the scores, so they cannot drift apart.

What the number is. A score describes how two signs relate in traditional astrology. It is not a prediction about two people and not advice about a relationship. It never changes for a particular couple, and nothing in it is random.

The four inputs

Each input is turned into a value between 0.00 and 1.00.

1. The angle between the signs

Count the signs from one to the other, the short way round the zodiac.

Signs apart	Name	Value	Reason
4	Trine	1.00	Called harmonious by Ptolemy. The two signs always share an element.
2	Sextile	0.85	The other harmonious configuration.
0	Same sign	0.75	Alike in everything: sympathy, without the complement a trine adds. Ptolemy does not rank it; this value is our choice.
6	Opposition	0.50	Called discordant, yet the two signs face each other across one axis.
3	Square	0.30	Called discordant.
1 or 5	Semi-sextile, quincunx	0.20	“Inconjunct”: the two signs have no configuration with each other.

Source: Ptolemy, Tetrabiblos, translated by J. M. Ashmand, Book I, chapters XVI (“Mutual configurations of the signs”) and XIX (“Signs inconjunct”). Ptolemy writes that “the trine and the sextile are each called harmonious” and that the opposition and the square are discordant.

2. The elements

Each element has two classical qualities: fire is hot and dry, air is hot and moist, water is cold and moist, earth is cold and dry. The value depends on which qualities the two share.

Elements	What they share	Value
The same element	Both qualities	1.00
Fire with air, earth with water	Hot or cold	0.75
Fire with earth, air with water	Dry or moist	0.40
Fire with water, earth with air	Neither	0.15

Sharing hot or cold counts for more than sharing dry or moist, because it matches the division into masculine and feminine signs that Ptolemy gives as the ground of harmony (Book I, chapter XV). The natures of the signs follow William Lilly, Christian Astrology (1647).

3. Steadiness

A fixed sign counts 1.00, a cardinal sign 0.50 and a mutable sign 0.00. A pair’s steadiness is the average of its two signs. Its adaptability is 1.00 minus its steadiness. Source: Ptolemy, Book I, chapter XIV, where the fixed signs are those in which the season is “more firmly established”.

4. The ruling planets

We use the seven traditional rulers, so Mars for Scorpio, Saturn for Aquarius and Jupiter for Pisces.

Add one point if both signs have the same ruler.
Add one point for each sign whose ruler is exalted in the other sign.
Take one point away for each sign whose ruler is in its fall in the other sign.

The total is kept between −2 and +2 and turned into a value: −2 gives 0.00, −1 gives 0.25, 0 gives 0.50, +1 gives 0.75, and +2 gives 1.00. A pair of the same sign is counted once.

Exaltations: the Sun in Aries, the Moon in Taurus, Mercury in Virgo, Venus in Pisces, Mars in Capricorn, Jupiter in Cancer, and Saturn in Libra. A planet’s fall is the opposite sign. Source: Ptolemy, Book I, chapters XX and XXII. The modern rulers are left out because the classical sources give them no exaltation.

The six facets

Each facet score is a weighted average of the input values, multiplied by one hundred and rounded to a whole number. The weights in each row add up to 1.00.

Facet	Angle	Elements	Steadiness	Adaptability	Rulers	Why
Love & romance	0.40	0.30	–	–	0.30	Attraction follows the configuration first; the rulers bring in the planets of desire and affection.
Trust	0.30	0.20	0.30	–	0.20	Fixed signs hold on to what is established, so steadiness counts as much as the angle.
Communication	0.30	0.35	–	0.25	0.10	A shared temperament makes two people easy to read; adaptable signs meet each other half-way.
Emotions	0.30	0.45	–	–	0.25	Temperament (hot, cold, moist, dry) is the classical account of feeling, so the elements lead.
Values	0.25	0.30	0.25	–	0.20	Lasting priorities: shared temperament and steadiness.
Shared activities	0.30	0.35	–	0.20	0.15	A similar level of energy, and a willingness to go along with the other’s plans.

The overall score is the plain average of the six facet scores as shown, rounded. You can check it with a calculator.

The sources tell us which inputs matter and in which direction. The weights themselves are our editorial judgement; no classical text prescribes them.

A worked example: Aries and Leo

Aries and Leo are 4 signs apart, a trine (1.00). Both are fire signs (1.00). One is cardinal and the other fixed, so steadiness is 0.75 and adaptability 0.25. Their rulers are Mars and the Sun, and the Sun is exalted in Aries: +1 point, a value of 0.75.

Love & romance: 0.40 × 1.00 + 0.30 × 1.00 + 0.30 × 0.75 = 92.5 out of 100, shown as 93
Trust: 0.30 × 1.00 + 0.20 × 1.00 + 0.30 × 0.75 + 0.20 × 0.75 = 87.5 out of 100, shown as 88
Communication: 0.30 × 1.00 + 0.35 × 1.00 + 0.25 × 0.25 + 0.10 × 0.75 = 78.75 out of 100, shown as 79
Emotions: 0.30 × 1.00 + 0.45 × 1.00 + 0.25 × 0.75 = 93.75 out of 100, shown as 94
Values: 0.25 × 1.00 + 0.30 × 1.00 + 0.25 × 0.75 + 0.20 × 0.75 = 88.75 out of 100, shown as 89
Shared activities: 0.30 × 1.00 + 0.35 × 1.00 + 0.20 × 0.25 + 0.15 × 0.75 = 81.25 out of 100, shown as 81
Overall: 93 + 88 + 79 + 94 + 89 + 81 = 524, divided by 6, shown as 87

Every overall score

Overall scores run from 24 (Virgo–Libra) to 87 (Aries–Leo and Libra–Aquarius).

	Ari	Tau	Gem	Can	Leo	Vir	Lib	Sco	Sag	Cap	Aqu	Pis
Aries	79	38	69	28	87	37	58	35	82	41	65	29
Taurus	38	80	30	75	42	77	35	59	38	82	33	74
Gemini	69	30	78	37	69	42	82	38	57	29	82	35
Cancer	28	75	37	79	30	69	41	72	34	58	38	86
Leo	87	42	69	30	80	38	65	33	82	38	59	30
Virgo	37	77	42	69	38	84	24	69	40	82	30	52
Libra	58	35	82	41	65	24	79	38	69	38	87	42
Scorpio	35	59	38	72	33	69	38	80	30	75	42	82
Sagittarius	82	38	57	34	82	40	69	30	78	32	69	37
Capricorn	41	82	29	58	38	82	38	75	32	79	35	64
Aquarius	65	33	82	38	59	30	87	42	69	35	80	38
Pisces	29	74	35	86	30	52	42	82	37	64	38	78

What the score cannot do

It uses Sun signs only. A person’s chart also has a Moon, Venus, Mars and more, and two people of “low-scoring” signs can have charts that fit well.
The angle between two signs settles a great deal: signs in trine always share an element, and signs in square always share a modality. So scores fall into bands by angle, and the other inputs move a pair within its band.
Several pairs end up with the same overall score.
Opposite signs score in the middle. Popular astrology often rates them higher; the classical sources call the opposition discordant, and our value sits between the two views.
It is not a reason to start, stay in or leave a relationship.

Sources

Ptolemy, Tetrabiblos, translated by J. M. Ashmand (1822), Book I, chapters XIV, XV, XVI, XIX, XX and XXII; Book IV, chapter V.
William Lilly, Christian Astrology (1647), on the natures of the twelve signs.

Found a mistake in the method or the arithmetic? Please tell us.