Synastry Method: What Is Calculated and Checked
How OpenFate compares two Western natal charts: cross-aspects within fixed synastry orbs, double contacts, house overlays, element balance and profection timing, with no invented score.
Overview
Both natal charts are calculated first. The synastry engine then lists the aspects between the two charts, where each person’s planets fall in the other’s houses, and how the two element balances combine. There is no compatibility score.
What is calculated
- Cross-aspects between the two charts’ planets and angles, using fixed synastry orbs, with a flag when the same pair of planets connects in both directions (double contact).
- House overlays: which house of each chart the other person’s planets occupy, in both directions.
- The combined element balance of the two charts.
- Timing windows from each person’s annual profection, reusing the single-chart profection calculation.
- Honesty flags that suppress angles and houses when a birth time is not reliable.
Fixed conventions and inputs
- Tropical zodiac, Placidus houses and the mean lunar node are used for both charts; the calculation settings of a single-chart reading are not applied here.
- Synastry orbs are a fixed, documented table and are not user-adjustable.
- Daylight-saving choices and the stated birth-time precision are applied per person.
How the report is written and checked
- The model receives the calculated contacts, overlays and timing and writes the explanation; no score is produced or allowed.
- Before a report is saved, every check runs: a reversed overlay (whose planet falls in whose house) blocks the report, and missing chart-ruler or warning coverage, timing mistakes, and numbers written as scores are all checked.
- Every compatibility report is also held to shared limits: unsupported claims of a rare bond, a whole-match grade above the classical band, and a report cut off before its last section are never saved. The other person’s feelings, fears and view of you are written only as chart tendencies to check in real life, and the two of you are never compared with other couples. If a draft fails only on such wording, top-degree words are toned down in place, sentences that state the other person’s inner life as fact are removed (Chinese and English reports), and the report is checked again.
Publisher verification results
A separately written replay applies the synastry rules to 362 seeded synthetic chart pairs, including pairs placed exactly at orb limits, house cusps and sign boundaries: every cross-chart aspect with its orb and tight or key flag, double contacts, house overlays in both directions, and the element blend.
- Pairs compared
- 362
- Identical under declared rules
- 362
- Disclosed alternatives
- 2
Under OpenFate's declared synastry orbs and body set, 362 of 362 pairs match on every contact, overlay and element count. The record also shows 2 alternatives other practitioners use — the wider natal orb table and leaving out Uranus, Neptune and Pluto — with how each would change the pairs. Those are disclosed, not counted as errors.
The replay takes planet and cusp positions as input; their accuracy is checked separately by the single-chart astrology replay. It checks the pair rules, observed on 2026-09-25, not transit timing, birth-time reliability or any interpretation. OpenFate performed this comparison. The downloadable record is a summary; implementation and full execution fixtures remain private. This is not third-party certification or a public replay kit.
Concepts in the OpenFate Wiki
Before you buy
- Both birth records are confirmed on a free preview before anything is charged.
- A complete report uses 65 credits. The credits are reserved when generation starts and returned automatically if the report cannot be completed.
- The saved report keeps the calculated facts it was written from, so later questions in the report chat read the same facts.
Limits
- Aspects describe symbolic interaction patterns, not guaranteed attraction or conflict.
- Without reliable birth times, houses and angles are withheld and the reading is narrower.