Planetary Aspects
See conjunctions, trines, sextiles, squares, and oppositions between your planets and your partner's planets. These aspects reveal the main energetic connections in the relationship.
Birth chart synastry
Free Synastry Chart Calculator
Compare your birth chart with your partner's chart and explore the planetary aspects, house overlays, and relationship patterns between you.
This birth chart synastry tool helps you generate a two-person astrology synastry chart using your birth dates, times, places, and an optional shared city for house overlays.
You
Your partner
Calculate Your Synastry Chart
Enter the birth details for both people to create a synastry chart. The calculator compares two natal charts and shows how your planets, houses, and angles interact.
Exact birth times give more accurate house overlays and ascendant details. If you do not know the exact time, you can use the default time and still compare the main planetary aspects.
Why Use This Synastry Chart Calculator
A synastry chart is the main relationship astrology chart for comparing two people. This synastry chart calculator keeps the process simple: enter both birth profiles, generate your synastry chart, and review the strongest aspects and house overlays in one place. This free synastry calculator is built around the synastry chart itself, not a generic score.
Use the synastry chart as your starting point before reading a longer interpretation. A synastry chart can show repeated relationship themes, while the full synastry chart interpretation explains how those themes may feel in real life.
Every synastry chart depends on two natal charts. Accurate birth dates, birth locations, and birth times help the synastry chart calculator create better angles, houses, and overlays.
Synastry Chart Results
What Your Synastry Chart Shows
A synastry chart compares two natal charts side by side. It highlights where your planets connect, where emotional or romantic chemistry may appear, and where tension or growth patterns may show up.
Use this synastry chart to read the relationship from several angles. The synastry chart wheel shows the overall pattern, the aspect table shows the strongest contacts, and the house overlays show which parts of life the relationship activates.
House Overlays
House overlays show where your partner's planets fall in your chart. This helps describe which life areas the relationship may activate, such as romance, communication, intimacy, or long-term growth.
Shared-City Ascendants
Use the shared city option to compare relocated ascendants and house placements for the same location. This is useful when you want to explore how the relationship energy may feel in a specific place.
Synastry Map View
Open individual or combined astrocartography maps to compare both people's planetary lines around the world.
Birth chart synastry
Birth Chart Synastry and Natal Chart Synastry
Birth chart synastry and natal chart synastry usually refer to the same relationship astrology method: comparing two people's natal charts to understand compatibility, attraction, emotional patterns, and potential challenges.
Instead of looking at one chart alone, astrology synastry studies how two charts interact. For example, your Sun may form a sextile to your partner's Jupiter, or your partner's Venus may fall in your 7th house. These connections help describe the tone of the relationship.
On this page, birth chart synastry, natal chart synastry, and free synastry chart results describe the same core workflow: calculate a synastry chart, compare both natal charts, and read the relationship patterns that appear between them.
Interpretation
Synastry Chart With Interpretation
After calculating your synastry chart, you can review the aspect table, chart wheel, house overlays, shared-city placements, and map view. These details help you understand the relationship from several angles instead of relying on one compatibility score.
For deeper guidance, you can unlock an AI interpretation that summarizes the major relationship themes based on your synastry aspects and optional relocation information.
A synastry chart with interpretation is most useful when it explains both harmony and tension. This synastry chart calculator gives you the chart data first, then lets you use the AI reading to turn the synastry chart into a clearer relationship summary. You can treat this page as a synastry chart calculator and interpretation guide, with the chart results first and the explanation second.
Reading guide
How to Read a Synastry Chart
1. Start With the Sun, Moon, Venus, and Mars
The Sun shows identity and vitality, the Moon shows emotional needs, Venus shows affection and attraction, and Mars shows desire and action. These planets are often the first places to look in relationship astrology.
2. Check the Aspect Type
Trines and sextiles often feel supportive or easy. Squares and oppositions can create friction, attraction, or growth. Conjunctions can feel powerful because both planets are working in the same area of the chart.
3. Look at the Orb
The orb shows how close an aspect is. A smaller orb usually means the connection is stronger and more noticeable.
4. Read the House Overlays
House overlays show where one person's planets land in the other person's chart. For example, Venus in the 7th house may emphasize partnership, while Mars in the 5th house may emphasize passion and playfulness.
5. Combine the Patterns
A single aspect does not define a relationship. A good synastry chart analysis looks at repeated themes across planets, houses, angles, and the overall chart pattern.
Free astrology tool
Free Synastry Chart Calculator for Relationship Astrology
Use this free synastry calculator to compare two charts online. You can generate the basic chart, review the aspect list, and explore the main relationship patterns without manually calculating planetary positions.
This synastry chart calculator is designed for astrology synastry, compatibility exploration, and personal reflection. It should not be treated as a fixed prediction of a relationship's outcome.
FAQ
Synastry Chart Calculator FAQ
What is a synastry chart?
A synastry chart is a relationship astrology chart that compares two people's natal charts. It shows planetary aspects, house overlays, and other connections that may describe attraction, emotional patterns, communication style, and relationship dynamics.
Is birth chart synastry the same as natal chart synastry?
Yes. In most astrology contexts, birth chart synastry and natal chart synastry mean the same thing. Both refer to comparing two birth charts to understand how two people's planets and houses interact.
Is this a free synastry chart calculator?
Yes. You can use the calculator to generate a free synastry chart and review the main chart details. Some advanced interpretation features, such as AI-generated relationship insights, may require login or credits.
Do I need an exact birth time for synastry?
An exact birth time is recommended because it affects the ascendant, houses, and house overlays. If you do not know the exact time, you can still compare the main planetary aspects, but the house-based interpretation may be less precise.
What does a synastry chart with interpretation include?
A synastry chart with interpretation usually explains the most important aspects between two charts, such as Sun-Moon connections, Venus-Mars attraction, Saturn patterns, emotional compatibility, and house overlays. This calculator shows the chart data first and can provide optional AI interpretation for deeper analysis.
What is the difference between a synastry chart and a composite chart?
A synastry chart compares two separate natal charts and shows how they interact. A composite chart creates a new combined chart from the midpoint between two people's planets. Synastry focuses on interaction; composite charts focus on the relationship as its own entity.
Is this a progressed synastry chart?
No. This page focuses on standard natal chart synastry, which compares two birth charts. A progressed synastry chart compares progressed planets and is a different technique.
Can I use this for synastry analysis free?
Yes. You can use the free chart results as a starting point for synastry analysis. The aspect table, chart wheel, and house overlays help you identify the strongest relationship patterns before moving into a deeper interpretation.
Calculate Your Free Synastry Chart
Enter both birth profiles above to compare your natal charts, review the strongest aspects, and explore your relationship patterns with a synastry chart. Your free synastry chart can then become the starting point for deeper synastry analysis free or AI-assisted interpretation.