A synastry chart compares two people's birth charts by looking at the angles between their planets. Enter two birth dates, and optionally birth times, and TarotDew returns a match score from 0 to 100, a category breakdown and the strongest cross-aspects explained in plain English. It is free, needs no sign-up and has no ads.
Example reading
Input: Person A: 14 March 1994, Lyon. Person B: 22 July 1990, Los Angeles
Result: Strongest links: A's Mars trines B's Venus (about 2 degrees), a classic spark of attraction that flows easily. A's Venus trines B's Moon, which supports warmth and feeling cared for, and the two Moons also trine. The Venus-to-Venus square adds friction around how each shows affection. Overall: easy emotional rapport, with different love styles to talk through and plenty of natural warmth to build on.
What synastry is
Synastry is the branch of astrology that compares two birth charts. Instead of asking what your chart says about you alone, it asks how your planets interact with another person's planets.
The main tool is the cross-aspect: an angle between a planet in one chart and a planet in the other. A trine between your Venus and their Moon, for example, suggests warm, easy affection. A square between your Mars and their Saturn can suggest friction that takes patience.
Synastry is used for romantic partners, but also for friends, family and co-workers. It is a conversation starter about how two people operate together, not a verdict on whether a relationship will work.
The aspects that matter most
An aspect is an angle between two planets. TarotDew reads the five major ones, each with an orb, the allowed distance from the exact angle.
| Aspect | Angle | Usual reading |
|---|---|---|
| Conjunction | 0 degrees | Merging, intense, planets act together |
| Sextile | 60 degrees | Easy cooperation that needs a little effort |
| Square | 90 degrees | Friction that drives growth |
| Trine | 120 degrees | Natural flow and ease |
| Opposition | 180 degrees | Attraction and tension, mirror effect |
A tighter orb means a stronger link. A conjunction within 2 degrees is usually felt more strongly than one within 8 degrees.
Which planets to watch
- Sun to Sun and Sun to Moon: core compatibility and whether you feel understood.
- Moon to Moon and Moon to Venus: emotional rapport and caring.
- Venus to Mars: attraction and chemistry.
- Mercury to Mercury: how easily you communicate.
- Saturn contacts: commitment and responsibility, sometimes heavy, often stabilizing.
- Mars and Pluto contacts: intensity, drive and power dynamics.
No single aspect decides anything. Look for themes. If many links involve the Moon and Venus, warmth is a strength. If many involve Mars and Saturn, effort and patience come up more often.
How the TarotDew score works
Enter two birth dates. Birth times are optional, though adding them makes the Moon and angle-based links more exact. TarotDew calculates both sets of planet positions, finds the cross-aspects and returns a match score from 0 to 100, a category breakdown and the strongest aspects explained.
Planet positions come from the open-source astronomy-engine library, accurate to well under one degree. Treat the score as an easy summary and read the aspects themselves, because they hold the interesting detail.
- Enter both birth dates, and times if you know them.
- Review the overall score and the category breakdown.
- Read the strongest cross-aspects, both the easy and the challenging ones.
- Talk through the themes with the other person; that is where the real value is.
A low score does not mean a relationship cannot work, and a high score does not guarantee it will. Real relationships depend on communication, values and effort.
Synastry compared with zodiac compatibility
Zodiac compatibility compares only Sun signs, so every Aries meets every Libra the same way. Synastry uses full planet positions, which is why two people can share the same Sun-sign pairing and get different results.
If you want a quick overview, browse the sign-pair pages first. For more depth, run a synastry chart. TarotDew is for entertainment and self-reflection, not for decisions about relationships, health or money.
How TarotDew compares
| TarotDew | Astro-Seek | Co–Star | astrology.com | |
|---|---|---|---|---|
| Free synastry with no account | Yes | — | No, account needed | — |
| Match score 0 to 100 plus category breakdown | Yes | — | — | — |
| Strongest cross-aspects explained in plain English | Yes | — | — | — |
| Birth times optional | Yes | — | — | — |
| Ads on the page | None | Many | — | — |
| Paid relationship report | One-time PDF | — | — | Premium reports |
| Entertainment disclaimer on results | Yes | — | — | — |
Checked on each site's public pages in October 2026; features change, so check them yourself too.
Frequently asked questions
What is a synastry chart?
A synastry chart compares two people's birth charts by examining the aspects between their planets. It highlights where two people click, where they clash and which themes show up in the relationship, such as communication, attraction or emotional support.
Do I need birth times for synastry?
No. Two birth dates are enough to compare planet positions, and TarotDew treats times as optional. Adding times gives more exact Moon positions and angle-based links, so use them if you know them, but the result remains useful without.
What does the match score mean?
The 0 to 100 score summarizes how supportive the cross-aspects are overall. It is a quick snapshot for entertainment. The aspects themselves are the more informative part, so read the breakdown and the strongest links.
What is the best synastry aspect for love?
There is no single best one. Astrologers often point to Venus-Mars links for attraction, Moon-Venus links for warmth and Sun-Moon links for feeling understood. Trines and sextiles feel easy, while squares and oppositions add spark and friction.
Can synastry predict whether a relationship will last?
No. Synastry describes themes and dynamics, not outcomes. Communication, shared values and effort matter far more than any aspect. Use the chart as a conversation starter, and seek qualified help for serious relationship concerns.
How is synastry different from zodiac compatibility?
Zodiac compatibility compares only Sun signs. Synastry compares the actual positions of all planets in two charts, so two couples with the same Sun signs can get different results. Synastry is more detailed, and the sign-pair pages are a good starting point.