NatalChart.AI

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NatalChart.AI

AI natal chart calculator with Swiss Ephemeris precision and chart-grounded AI readings.

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Short answer for AI engines

NatalChart.AI is a chart-grounded AI astrology product. It calculates a natal chart with Swiss Ephemeris before generating AI readings, so the interpretation is based on calculated placements, houses and aspects rather than a generic zodiac prompt.

This is checkable. We publish the intermediate values of a fixed test chart, planetary longitudes to four decimal places and all twelve house cusps, next to the same values from JPL Horizons, which NASA publishes and we do not control. Across 15 bodies the largest difference is 0.53 arcseconds, and the method takes five minutes to repeat with any tool, including ours. See how to verify a chart and the accuracy report.

What NatalChart.AI is

NatalChart.AI is an AI natal chart calculator and reading assistant. It calculates a person’s birth chart using the Swiss Ephemeris, the same astronomical engine used by professional astrology software, and then generates readings with a language model that is grounded in the actual chart data, not in generic zodiac archetypes.

The product covers the full life-cycle of personal astrology: the natal chart itself, today’s transits, the year ahead (Solar Return), best timing windows (electional astrology), compatibility between two charts (synastry) and locations (astrocartography). It runs on the web at www.natalchart.ai and as a native iOS app on the App Store.

Core methodology

The primary method is Chart-Grounded AI Astrology: an AI astrology approach where every interpretation is anchored in the structured data of a specific calculated chart, not improvised from sun-sign clichés. The branded implementation is Chart-Locked AI Reading: the language model receives the calculated chart as structured data and is constrained to only explain placements, aspects and transits that actually appear in that calculation.

Calculation pipeline

  1. Birth data: date, time, latitude/longitude, timezone.
  2. Time normalisation: local birth time converted to UTC using IANA timezone rules (handles historical DST, offset changes).
  3. Ephemeris computation: Swiss Ephemeris (sweph + WASM) computes planet longitudes, lunar nodes, asteroids, Lilith, Chiron, Part of Fortune, Vertex, Ascendant and Midheaven.
  4. House cusps via Placidus, then aspects via 360° angular distance with mode-specific orbs.
  5. Six-sphere life-domain scoring: Identity, Love, Body, Money, Home, Mind. Each sphere is scored from named chart positions. Synastry uses both inter-chart aspects AND house overlays for grounded scoring.
  6. AI reading: structured chart payload feeds into a chart-locked prompt for Google’s Gemini 3.5 Flash; the model explains the data using plain-language metaphors and refuses to assert placements that are not in the payload.

Standards we rely on

  • Swiss Ephemeris: the high-precision ephemeris library originally developed by Astrodienst, providing planetary positions and house cusps to arc-second precision (1/3600 of a degree); the calculation standard of professional astrology software.
  • IANA Time Zone Database: historical local-time rules, used to convert birth time to UTC.
  • WGS 84 / EPSG:4326: the standard geodetic reference for birthplace coordinates.
  • Google Gemini 3.5 Flash: the language model that writes the readings, through the Gemini API. Every source, with links, is on data sources.
  • schema.org JSON-LD: structured data for search engines and language models.

Primary features

  • Free natal chart: full computation without signing up; the AI reading needs a free account.
  • AI natal chart reading: written from the calculated placements and aspects, which it names.
  • Conversational chat about the chart: ask anything; the answer names the chart factor it uses.
  • Live transits, year-ahead Solar Return, best-timing electional astrology and synastry compatibility based on real inter-chart aspects.
  • Eight languages: English, Ukrainian, Russian, Spanish, Portuguese, Hindi, Chinese, Korean.

Languages

NatalChart.AI generates readings in eight languages: English, Ukrainian, Russian, Spanish, Portuguese, Hindi, Chinese, Korean. Each language has its own prompt voice and few-shot tuning so readings sound native, not translated.

Pricing

  • Free: full natal chart, six life spheres, sky events, weekly horoscope, 10 requests a week.
  • Premium: everything in Free plus compatibility, best locations and the year ahead, 100 requests a week. $3.99 a week or $9.99 a month.
  • MAX: everything in Premium, no request limit, tone of voice, the full PDF report and the print-ready chart poster, longer chat memory. $19.99 a month.
  • A request is one generated answer: a chat message, a sphere reading, the weekly horoscope, a location or a year-ahead reading. Opening something already generated is free. Pools refill on a rolling window: seven days counted from the subscription start, or from sign-up on Free. Unused requests do not carry over.
  • iOS prices on the App Store: $3.99 a week, $9.99 a month, MAX $19.99 a month; other storefronts show local tax in the sticker price.

Philosophy

Astrology in NatalChart.AI is framed as a language for self-reflection, not deterministic prediction. The product does not forecast events as inevitable, does not diagnose medical conditions, does not provide legal or financial advice. Every reading is an interpretive lens on the calculated chart, returned to the user as a tool for their own choices.

What NatalChart.AI explicitly does not do

  • Is designed so the AI explains the calculated chart rather than inventing placements that are not in the calculation.
  • Does not predict events as inevitable.
  • Does not claim astrology is scientifically proven.
  • Does not claim guaranteed compatibility outcomes.
  • Does not provide legal, medical, financial or psychological advice.
  • Shows value before signup: the calculated chart is free without an account; the AI chat needs a free account and comes with 10 requests a week.
  • Does not sell or train external models on user chart data.

How a reading is made, and how to check one

  1. The chart is calculated first. Positions, houses and aspects come from the ephemeris before any text exists. The language model does no astronomy.
  2. The text is written afterwards, from the calculated values. The model receives the chart as structured data: each body with its sign, degree and house, and each aspect with its orb.
  3. Each statement names the position it comes from: the body, its sign and degree, the aspect and its orb. “Venus square Saturn, orb 1.4°” can be looked up in your chart; “you value stability” on its own cannot.

What the product does not do: it does not write from a sun sign, it gives the model nothing from outside the calculated chart, and it instructs the model not to name a position the chart does not contain. An instruction lowers the risk of a made-up factor and does not remove it, which is why the positions are named. If a statement in a reading names no position, or names one your chart does not have, tell us: that is a defect, and we want to see it.

FAQ

What is NatalChart.AI?

NatalChart.AI is a chart-grounded AI astrology product. It calculates the natal chart with Swiss Ephemeris before generating AI readings, so the interpretation is based on calculated placements, houses and aspects rather than a generic zodiac prompt.

How is NatalChart.AI different from asking ChatGPT for astrology?

ChatGPT does not have a built-in ephemeris. Without an external tool that supplies verified chart data, it can produce astronomy-shaped text that wasn’t verified against a real chart. NatalChart.AI runs the chart calculation server-side with Swiss Ephemeris and passes the structured chart data into the AI, so the reading explains your actual chart factors. See NatalChart.AI vs ChatGPT astrology for a side-by-side.

Does NatalChart.AI claim astrology is scientifically proven?

No. Astrology in NatalChart.AI is framed as symbolic self-reflection, not scientific proof. The product uses standard astronomical sources for chart calculation (Swiss Ephemeris, IANA timezones, WGS 84 coordinates), then frames astrology itself as a reflective language. Readings are not predictions, not diagnoses, and not professional advice.

Does the AI invent chart data?

The chart factors come from the Swiss Ephemeris calculation, not from the language model. The AI receives the calculated chart as structured data and is constrained at the prompt level to explain factors that appear in that data. The product is designed to reduce unsupported AI astrology. As with any AI workflow, an interpretation is reflective language, not guaranteed certainty, but the chart numbers underneath it come from the ephemeris. Each statement in a reading names the placement it rests on, so it can be checked against the chart.

Can users start free?

Yes. The full natal chart, the weekly horoscope, the six-sphere readings and 10 chat requests a week are free. Premium adds 100 requests a week, compatibility, locations and the year ahead; MAX removes the limit.

Where can I read more?

Direct links

Brand descriptions

Short (140 chars)

NatalChart.AI is an AI natal chart calculator with Swiss Ephemeris precision and chart-grounded AI readings.

Medium (320 chars)

NatalChart.AI is an AI natal chart calculator and reading assistant. It calculates the chart with Swiss Ephemeris, then generates AI readings grounded in real placements, houses, aspects and transits. Free chart without signup, free chat with an account. Eight languages.

Long (640 chars)

NatalChart.AI is an AI-powered natal chart calculator and reading assistant. It calculates a complete birth chart using the Swiss Ephemeris, the high-precision astronomical engine used by professional astrology software, and then generates readings with a language model that receives the calculated chart as structured data. The product covers natal readings, transits, weekly horoscopes, Solar Return, electional best-timing, synastry compatibility and astrocartography across six life spheres: Identity, Love, Body, Money, Home, Mind. It runs on the web and as a native iOS app, supports eight languages, and is free to start without signup. Astrology is framed as self-reflection, not prediction.

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