About this calculator
A small independent project that computes birth charts from real ephemeris positions and explains them in plain language.
How the chart is calculated
Positions come from an astronomical ephemeris, not a lookup table of sign dates. When you enter a date, time and place, the engine computes the ecliptic longitude of the Sun, the Moon and nine further bodies for that instant, then places them in signs and houses.
The conventions are the tropical zodiac and whole sign houses — the oldest house system in Western astrology, and the reason your house placements here may differ from a site that defaults to Placidus. Both choices are stated rather than hidden, because a chart is only reproducible if you know which conventions produced it.
Your birth details never leave your device
This is the part worth being specific about. The calculation runs entirely in your browser: the astronomy engine is downloaded to your device and executed there, and your date, time and place of birth are never sent to a server, ours or anyone else’s.
There is no account, no login and no email gate, and nothing you type into the calculator is written to a cookie or to local storage — closing the tab discards it.
The site does load Google Analytics through Tag Manager, so that we can see which pages people actually reach. It measures pages, not people: it never receives your birth details, because those are never sent anywhere for it to receive. Across the EEA, the UK and Switzerland it runs without setting any cookie at all. The full detail is on the privacy page.
Where the readings come from
The interpretations are written in advance by a person and selected by the placements the engine calculates. Nothing is generated live while you wait, and no language model is running behind the page when you request a reading.
That is a deliberate trade: you get text that has been read and edited before it reached you, rather than text assembled on the spot that nobody has checked.
What this is not
Astrology is a symbolic tradition, not a measurement of anything about you. The astronomy underneath is real and checkable; the meaning laid on top of it is interpretation.
Nothing here is advice about your health, your finances or your future, and no reading is a substitute for a qualified professional. Use it the way most people actually use a chart — as a frame for thinking about yourself, and nothing heavier than that.
Common questions
- Is the calculator really free?
- Yes. Calculating your chart and seeing your Sun, Moon and Rising signs costs nothing and requires no account. There is an optional paid reading, which is a longer written interpretation of the placements the free calculation produced.
- How do I get in touch?
- Email admin@natalchartonline.com. Corrections to the astronomy or the copy are genuinely welcome — if something computes wrong, we would rather hear about it.