Free birth chart calculator
Enter your birth date, time and place. You will get a complete natal chart — planets, houses, aspects and the drawing — plus an honest note about how well your birth time could actually be resolved.
What you get
A full chart wheel with the ten classical bodies, all twelve house cusps and the major aspects between them, in any of seven house systems. Nothing is held back behind a signup: the chart itself is free and complete, and always will be.
Two people, or today’s sky?
The synastry calculator lays two charts over each other: every aspect between one person’s planets and the other’s, and where each person’s planets fall in the other’s houses. The transit calculator does the same with the sky on any date against your chart.
Why we show you the timezone we used
Most chart sites quietly guess. Historical daylight saving is genuinely uncertain — the international timezone database says outright that its pre-1970 records “cover only a tiny sliver of how clocks actually behaved”, and one of the largest astrology services estimates about one percent of charts would be wrong if you relied on it alone.
So we show you the UTC offset we used, tell you how confident we are in it, and let you correct it. If you were born before 1970 in the United States or Canada — where the records are thinnest — we say so rather than pretending otherwise.
If you want the detail
Four things people ask about charts that deserve more than a paragraph, answered from what this engine measurably does rather than from received wisdom:
- Why two sites give you different charts — four causes, in order of how often they are the culprit, and how to tell which.
- What your rising sign is, and why the minute matters — including why some rising signs are three times commoner than others.
- You don’t know your birth time — what a chart can still tell you, and where the time is actually written down.
- House systems, and which one to choose — what each divides, and which stop working near the poles.
Questions
- What if I don’t know my birth time?
- You can still get a chart. We use noon as a stand-in and say so clearly. Your planetary positions will be right, because the planets move slowly, but the rising sign and every house placement depend on the exact minute and will not be reliable.
- Why does my birth time matter so much?
- The rising sign moves about one degree every four minutes, so an hour of error shifts it roughly fifteen degrees and can change the sign entirely. Every house placement follows from the rising degree, so one wrong minute quietly changes most of the chart.
- Which house system should I choose?
- Placidus if you have no reason to prefer another — it is the modern Western default and what most astrologers will assume. Whole sign is the traditional and Hellenistic choice. Equal houses stay well defined at high latitudes, where Placidus breaks down.
- How accurate are the calculations?
- Planetary positions agree with NASA JPL Horizons to within 0.3 arcminutes, and the angles and house cusps agree with Swiss Ephemeris to within 0.05 arcminutes. For scale, one arcminute of rising degree is four seconds of birth time.