Reviewed by Dr. L. Nageshwwar Rao, PhD (Astrology), Consulting Astrologer · Last reviewed 5 August 2026 · How we compute this
Free synastry calculator. Every cross aspect between two birth charts — each of Person A's planets against each of Person B's — plus composite midpoints.
Fill in both sets of birth details first — each one is validated and saved on its own, then the two charts are compared in a single request.
Synastry is the comparison of two birth charts by the geometric contacts between them. For every body of Person A and every body of Person B, the calculator works out the angle between the two points and reports the aspect (conjunction, sextile, square, trine or opposition) when it falls within orb. A contact is a fact about the sky at the two birth moments — it is not a verdict on the relationship, and this page never turns contacts into a compatibility score or a percentage.
The grid is the full A × B comparison: each row pairs one of Person A's bodies (the left column) with one of Person B's bodies (the right column) that forms an aspect within orb, with the aspect type, the angle, the orb, and whether the contact is applying or separating. Person A is always the first chart you entered, and the same 10 bodies are used for both sides: the seven classical planets, the lunar nodes and Pluto.
The composite list shows one midpoint per body: the point exactly halfway between Person A's and Person B's positions of the same planet, with its sign and degree. Each midpoint is a geometric fact of the two charts. Composite houses and angles are deliberately not computed here — the two charts are read from two different ascendants, and competing house systems would assign the same midpoint to different houses, so a composite house would be an invention rather than a computation.
They describe the direction of the contact at the moment of birth. An applying contact means the gap between the two bodies and the exact aspect angle is still closing; a separating contact means they have already passed it. Both are pure geometry — in synastry the two charts are fixed at their birth moments, so the distinction records the relative speed of the bodies at those instants and adds no meaning or weight to the contact.
No. It computes the geometric contacts between two charts and nothing else: no compatibility score, no percentage, no verdict on the relationship, and no prediction of how it will go. Aspects in a synastry grid are alignments, not judgements — weighing them against the two charts as wholes is the work of an astrologer's reading, not of an arithmetic sum.
Gun Milan (Kundli Milan) is the Vedic matching system: an 8-factor, 36-point Ashtakoot scoring of the two sidereal charts, used traditionally before marriage. This page works in the tropical zodiac and shows geometric contacts only — no score. The two systems also measure the zodiac from different starting points (about 24 degrees apart), so a planet's sign can differ between them. If you came here looking for the Vedic match score, use the Gun Milan / Kundli Milan calculator instead.
Festival dates, muhurta tips and the occasional reading offer. No spam — unsubscribe anytime.
