Ashtakoota Milan uses the Moon sign and birth Nakshatra of both partners — not the Sun sign, not the full birth chart, and not the Ascendant. The Moon is used because it governs the mind, emotional instincts, and the relational self — the dimensions of a person that are most directly experienced in long-term partnership. Two people can have compatible Sun signs and still be emotionally incompatible at a fundamental level. The Moon and Nakshatra reveal this layer.

Each of the eight Kootas is calculated from a specific attribute of the Nakshatra: its Gana (temperament group), Yoni (animal symbol), Nadi (Ayurvedic constitution), the ruling planet of its sign, and the numerical relationship between the two Nakshatras. The eight scores are summed to give the total Guna Milan score out of 36.

Varna (वर्ण — "category" or "class") is the lowest-weighted Koota, carrying only 1 point. It assigns each Nakshatra to one of four Varnas — Brahmin (highest, associated with spiritual and intellectual work), Kshatriya (warrior and administrative), Vaishya (commercial and agricultural), and Shudra (service). This classification is not a social hierarchy in the contemporary sense — it describes the dominant life orientation and psychological archetype of the Nakshatra.

For full Varna compatibility, the groom's Varna should be equal to or higher than the bride's in the traditional system. If both are the same Varna, the score is 1. If the groom's Varna is higher, the score is 1. If the groom's Varna is lower than the bride's, the score is 0. Because Varna carries only 1 point, a mismatch here has minimal impact on the overall score but classically indicates a difference in fundamental life orientation.

Vashya (वश्य — "control" or "influence") measures the natural power dynamic and mutual attraction between partners. Each Moon sign is assigned to one of five groups — Manava (human: Aries, Taurus, Gemini, Virgo, Libra, Sagittarius first half, Capricorn first half), Chatushpada (four-legged animals: Leo, Sagittarius second half, Capricorn second half, Aries first half in some systems), Jalachara (water creatures: Cancer, Pisces, Capricorn second half), Vanachara (forest creatures: Leo), and Keeta (insects: Scorpio). Compatibility is determined by the natural relationship between the two groups.

A full score of 2 indicates mutual Vashya — both partners naturally influence and attract each other in a balanced way. A score of 1 indicates one-directional Vashya — one partner is naturally more drawn to the other. A score of 0 indicates no natural Vashya — the partners do not naturally inspire attraction or influence in each other, which can lead to emotional distance over time.

Tara (तारा — "star") is calculated by counting the position of the groom's birth Nakshatra from the bride's birth Nakshatra, and then the bride's from the groom's — in both directions. The 27 Nakshatras are grouped into nine cycles of three (called Taras): Janma (1st, 10th, 19th), Sampat (2nd, 11th, 20th), Vipat (3rd, 12th, 21st), Kshema (4th, 13th, 22nd), Pratyak (5th, 14th, 23rd), Saadhaka (6th, 15th, 24th), Naidhana (7th, 16th, 25th), Mitra (8th, 17th, 26th), and Parama Mitra (9th, 18th, 27th).

The Kshema (4th), Saadhaka (6th), Mitra (8th), and Parama Mitra (9th) Taras are auspicious. The Vipat (3rd), Pratyak (5th), and Naidhana (7th) Taras are inauspicious — indicating potential health challenges, obstacles, and danger respectively in the relationship. Janma (1st) and Sampat (2nd) are neutral to positive. When counted in both directions and both results are auspicious, the full score of 3 is awarded. Mixed results give 1.5. Both inauspicious gives 0.

Yoni (योनि — "womb" or "source") measures physical and intimate compatibility. Each of the 27 Nakshatras is assigned an animal symbol — 14 animals in 14 pairs, each Nakshatra sharing its animal with one other Nakshatra of the opposite gender. The 14 Yoni animals are: Horse, Elephant, Sheep, Serpent, Dog, Cat, Rat, Cow, Buffalo, Tiger, Hare, Monkey, Mongoose, and Lion.

Full compatibility (4 points) means both partners share the same Yoni animal — a perfectly matched pair. High compatibility (3 points) means the Yoni animals are natural friends. Average (2 points) means the animals are neutral to each other. Low (1 point) means the animals are natural enemies. Zero points means the pair is a hostile Yoni match — for example, Cat and Rat, or Dog and Hare — indicating deep physical and temperamental incompatibility that tends to produce friction even when other Kootas score well.

Graha Maitri (ग्रह मैत्री — "planetary friendship") measures psychological and intellectual compatibility — the quality of mental communication and mutual understanding between partners over the long term. It is calculated from the lords of both partners' Moon signs and their natural relationship to each other in the classical planetary friendship table.

If both Moon sign lords are mutual friends (naisargika mitra), the score is 5. If one is a friend to the other but not reciprocated, the score is 4. If both are neutral to each other, the score is 3. If one is an enemy of the other, the score is 1. If both are mutual enemies, the score is 0 — indicating a fundamental incompatibility in how both partners think and process the world, which tends to produce persistent intellectual friction and misunderstanding regardless of emotional effort.

Graha Maitri is one of the more practically significant Kootas because its domain — long-term mental harmony and intellectual respect — is essential for a stable marriage. Many astrologers treat it as second in importance only to Nadi.

Gana (गण — "group" or "category") measures temperament compatibility — the fundamental operating style and psychological character of both partners. Each Nakshatra belongs to one of three Ganas established in classical texts: Deva (divine — gentle, adaptable, spiritually inclined, cooperative), Manushya (human — worldly, practical, family-oriented, ambitious), and Rakshasa (fierce — intense, driven, strong-willed, boundary-challenging).

Same Gana partners score the full 6 points — deeply compatible temperaments that operate in natural rhythm with each other. Deva-Manushya is acceptable (4 points in some systems, 0 in stricter ones — this varies by regional tradition). Manushya-Manushya is compatible (5 points). Rakshasa-Rakshasa can work when both partners understand each other's intensity (6 points). Deva-Rakshasa is the most challenging combination — the gentle Deva temperament and the fierce Rakshasa temperament create sustained friction in daily life, scoring 0 in strict systems.

Bhakoot (भकूट — "Moon sign group") is the second-highest weighted Koota at 7 points. It measures emotional compatibility, financial harmony, and the prospects for children — all based on the relative positions of the two partners' Moon signs counted from each other.

The positions from each other are evaluated: 1/1 (same sign), 1/7 (opposite signs), 2/12, 3/11, 4/10, 5/9, and 6/8. The most critical Bhakoot Doshas are:

Bhakoot Dosha is cancelled under specific conditions: when both Moon sign lords are the same planet (e.g., both Aries and Scorpio ruled by Mars in some systems), or when the Moon sign lords are mutual friends. The cancellation conditions vary by regional tradition.

Nadi (नाड़ी — "pulse" or "channel") is the highest-weighted Koota, carrying 8 of the 36 total points. It measures physiological and genetic compatibility — the most fundamental biological layer of the compatibility assessment. Each Nakshatra belongs to one of three Nadis derived from Ayurvedic medicine: Vata (air constitution — Ashwini, Ardra, Punarvasu, Uttara Phalguni, Hasta, Jyeshtha, Moola, Shatabhisha, Purva Bhadrapada), Pitta (fire constitution — Bharani, Mrigashira, Pushya, Purva Phalguni, Chitra, Anuradha, Purvashadha, Dhanishtha, Uttara Bhadrapada), and Kapha (water constitution — Krittika, Rohini, Ashlesha, Magha, Swati, Vishakha, Uttarashada, Shravana, Revati).

When both partners share the same Nadi, Nadi Dosha is formed — scoring 0. This is the most serious single penalty in the Ashtakoota system. Classical texts associate same-Nadi matching with physiological incompatibility, health difficulties in children, potential for separation, and an overall sense of incompatibility that persists despite emotional effort. Different Nadi partners score the full 8 points.

Because Nadi Dosha carries 8 points — the most of any Koota — its presence significantly reduces the effective Guna score. A couple scoring 28/36 raw but with Nadi Dosha has an effective compatibility of 20/36, which falls in the marginal range. This is why experienced Jyotishis check Nadi before looking at any other Koota.

The Ashtakoota Guna score is the entry point of compatibility assessment, not its conclusion. Classical Jyotish practitioners always examine additional factors that the 36-point system does not capture:

A couple with a moderate Guna score of 22 but strong 7th houses, excellent Venus and Jupiter placements, and harmonious D9 charts will often sustain a more stable marriage than a couple scoring 30 with afflicted 7th lords and weak karakas. The Guna score is the beginning of compatibility analysis — a good Jyotishi always goes deeper.