Birth Chart Compatibility: Compare Two Charts

The calculator uses tropical geocentric positions and whole-sign houses. Each input uses the selected IANA time zone, including historical rules available in your browser. Repeated clock times require an earlier/later choice. Approximate times keep their uncertainty attached to the output.

Inter-chart aspects compare one person’s placements with the other person’s placements. Conjunction, sextile, square, trine and opposition are included. Your chosen 3, 6 or 8-degree tolerance applies equally to every pair. The default view compares five personal bodies. The all-bodies option includes Jupiter, Saturn, Uranus, Neptune and Pluto.

Each wheel displays an individual natal chart. Selecting an inter-chart aspect highlights its planet on each wheel. Lines within each wheel describe that person’s natal aspects using the birth-chart tool’s 6-degree rule. House numbers belong to each individual’s whole-sign chart.

If either time is unknown, the comparison shows possible signs across the local birth date. Degree-based comparisons become available when both times are supplied. Prompts use astrological symbolism. Learn about synastry, aspect geometry and houses.

Calculations use Astronomy Engine 2.1.19, MIT license. City data comes from GeoNames, CC BY 4.0, downloaded 12 November 2026. The city list covers places with at least 15,000 residents or designated capitals. Manual coordinates support other places. See the privacy policy for site-wide analytics and cookies.