True Node Astro

Free synastry chart calculator

Enter two people’s birth details. You get both charts, every aspect between them, and where each person’s planets fall in the other’s houses — drawn as one wheel.

First person

The rising sign moves about one degree every four minutes, so this matters more than anything else on the form.

Pick the closest town. A few kilometres makes no visible difference to the chart.

Second person

The rising sign moves about one degree every four minutes, so this matters more than anything else on the form.

Pick the closest town. A few kilometres makes no visible difference to the chart.

One house system for both. Each person’s planets are placed in the other person’s houses, so the houses have to mean the same thing on both sides.

What you get

A bi-wheel: the first person’s houses and planets in the middle, the second person’s planets on the outer ring, and only the aspects between the two drawn across it — the natal aspects each of you can see on your own chart are left out so the lines that matter here are legible. Under it, the full aspect list with orbs, and two tables of each person’s planets in the other’s houses.

What we do not do yet

Interpretations. There is no written reading for synastry aspects on this site yet, and we would rather show you the measured comparison than pad it. The natal chart has a short reading; this page has the numbers.

Two birth times, resolved separately

Each person’s time is converted to universal time from their own birth place, with its own historical timezone rules, and the page tells you how confident it is about each. One uncertain birth time does not spoil the other person’s chart.

Questions

What is a synastry chart?
Two birth charts laid over each other. It shows the aspects between one person’s planets and the other’s — their Moon square your Saturn, your Venus trine their Sun — and where each person’s planets fall in the other’s houses. Those two tables are what a synastry reading is made of.
Do I need both birth times?
You get more with them. Without a birth time we use noon. That person’s slow planets are still right, but their Moon moves about half a degree an hour, so by the end of the day it is six or seven degrees from where noon puts it — aspects to their Moon can appear, vanish or change. Their rising sign and houses are not reliable either, and the table of the other person’s planets in their houses depends on those houses. Everything except that person’s Moon holds up.
Which orbs do you use?
The same as the natal chart: 8° for conjunctions and oppositions, 7° for trines and squares, 5° for sextiles, 3° for quincunxes and 2° for semisextiles. Each pair of planets gets at most one aspect, the tightest that fits.
Is anything saved?
No chart is stored. Both people’s birth data travel in the page address, so the page is rebuilt from it each time and we keep no copy — though the address itself can appear in ordinary server access logs, as the privacy page explains. The result page is not indexed and does not send its address to other sites.