Free astrology calculators and tools

Which astrology calculator should I start with?

Start with the birth chart calculator. Everything else on this page either reads from your chart (compatibility, Saturn return, Personal Codes, transits) or sits alongside it (numerology, biorhythms, BaZi). Once you know your Sun, Moon and rising sign, the other results have somewhere to land; before that they are just numbers.

A useful order if you have twenty minutes: birth chart first, then the archetype quiz to see how your Big Three combine into one pattern, then the compatibility calculator with someone you are curious about, then the Saturn return calculator if you are anywhere between 27 and 31 or 56 and 60.

Tools by the question you are asking

• What are my Big Three? The birth chart calculator, then the rising sign guide for why the Ascendant changes everything.
• Are we compatible? The compatibility calculator for Western synastry, Chinese zodiac compatibility for the animal-sign view, and biorhythm compatibility for day-to-day rhythm.
• Why does my life feel like a renovation? The Saturn return calculator.
• What kind of year is this for me? The personal year calculator.
• What is in the sky right now? The Cosmic Simulator and the calendar for today.
• I want numbers I can actually use. Personal Codes for a goal, lucky numbers for today for the day.
• Which archetype am I? The archetype quiz.
• ¿Qué signo soy? The calculadora de carta natal and qué signo soy, written in US Spanish, not translated.

How our browser tools work (and their limits)

Every calculator here runs in your browser. Nothing you type is sent to a server, there is no account, and you do not need to leave an email. That is deliberate: these are previews of what the AstraLink app computes from your full birth data, and we would rather you try the logic before you trust it.

Because they run client-side, they make a few simplifications you should know about:

• Sun sign is exact for every date, including cusp days, because the tool computes the Sun's longitude for your birthday rather than looking it up in a fixed date table.
• Moon sign is close but not always exact. The Moon moves about 13° a day, so on a day when it changes sign, a birth without a time can fall either side of the line. The app resolves this with your exact time and place.
• Rising sign needs a birth time and a location. The browser tool estimates it from local time and a city look-up; the app uses precise coordinates and historical time-zone rules, which matters for births before the 1970s or during daylight-saving changes.
• Houses are not shown in the previews. The app uses Placidus by default.
• Compatibility in the browser scores Sun and Moon contacts. The app runs full synastry (Venus, Mars, Saturn, the nodes, house overlays) and explains each factor; read how synastry works for the method.
• Saturn return windows are computed from Saturn's actual ephemeris position, not the "every 29.5 years" shortcut. Saturn has been in Aries since 14 February 2026, so anyone born with Saturn in Aries (roughly 1996–1999, and 1967–1969) is in or entering a return now.
• Transits in the Cosmic Simulator preview show today's sky for everyone; the app overlays it on your natal chart with orbs and an AI reading of each contact.
• Numerology and biorhythm tools are exact. They need only your birth date, and the arithmetic is deterministic.
• BaZi (Four Pillars) uses the Chinese solar calendar and standard stem-branch tables. The hour pillar needs your birth time, and the year pillar changes at Lichun (around 4 February), not at Lunar New Year.

None of these tools give medical, legal or financial advice, and none of them predict events. They describe patterns and timing in the language of astrology and numerology, and you decide what to do with that.

Methodology in one paragraph

Tropical zodiac; Placidus houses in the app; ephemeris-grade positions; conventional orbs, tighter for minor aspects. Numerology uses the Pythagorean system. Chinese tools use the solar calendar. Where a result depends on a birth time we do not have, the tool says so rather than guessing, and the app asks for it. Our editorial policy explains how each calculator is reviewed, and the glossary defines every term the results use.

Want the full version?

The app computes everything above from your exact birth data, keeps it in one place, and adds what a browser cannot: an AI Advisor that takes a topic and a date, Personal Codes with strength scores and planetary breakdowns, live transits with interpretation, and compatibility with anyone, including people you have not met yet. Every tool on this page has a full counterpart in the app, and the results carry over. Join early access and your full chart is free on day one.