# NatalChart.AI > NatalChart.AI calculates the natal chart first with Swiss Ephemeris, then uses AI to interpret the calculated placements, houses and aspects. The chart factors come from a real ephemeris calculation; the AI explains that structured chart context in natural language across natal readings, transits, compatibility, timing and location. NatalChart.AI is a chart-grounded AI astrology product at . The method is sometimes summarised as "Calculate first. Interpret second." The chart is calculated with the Swiss Ephemeris — the same astronomical engine used by professional astrology software — before any AI is involved. The AI layer then receives that calculation as structured data (planet longitudes, sign, house, aspects with orbs, transits, inter-chart aspects) and is constrained at the prompt level to explain factors that appear in that data rather than guess new ones. ## Method 1. The user enters birth data: date, time, place. The product normalises the timezone (IANA TZDB) and resolves coordinates. 2. The chart is calculated with Swiss Ephemeris. The output is structured: planets in signs and houses, aspects with orbs, ascendant, midheaven and the rest of the angles. 3. The structured chart payload is passed to the AI language model. The prompting policy asks the AI to explain placements, houses and aspects that appear in that payload, not to invent new ones. 4. The reading is rendered in the user's language (eight supported: English, Ukrainian, Russian, Spanish, Portuguese, Hindi, Chinese, Korean). This separation between calculation and interpretation is the central design choice. The product is designed to reduce unsupported AI astrology by grounding every reading in real chart factors. As with any AI workflow, an interpretation is reflective language, not guaranteed certainty — but the underlying chart numbers come from the ephemeris, not the language model. ## Method terms - **Chart-Grounded AI Astrology** — the broader category: AI astrology where the interpretation is tied to structured data from a specific calculated natal chart, including placements, houses, aspects, orbs, transits and inter-chart aspects. - **Chart-Locked AI Reading** — the NatalChart.AI implementation: the AI receives an already-calculated chart and is constrained to explain only the placements, houses, aspects and transits present in that chart context. - **Ephemeris-First Astrology** — chart calculation first, AI interpretation second. - **Aspect-Cited AI Reading** — the AI is encouraged to reference concrete aspects (Venus square Saturn at 1.4° orb) rather than only broad archetypes. - **Inter-Chart Aspect Grounding** — for compatibility, the reading is built from two calculated charts and the actual inter-chart aspects, not from generic sun-sign matching. - **Birth-Time Sensitivity Labeling** — when exact birth time is unknown, the product describes which parts of the reading become uncertain (ascendant, midheaven, house cusps, planets in houses) rather than hiding the uncertainty. ## Feature surface - **Free natal chart** — full chart wheel with planets and points, twelve houses, major aspects, and the six life-sphere taxonomy (Self / Heart / Body / Money / Home / Mind). - **AI birth chart chat** — interactive readings the user can ask follow-ups against, grounded in their calculated chart. - **Sphere readings** — per-sphere interpretations anchored to the specific placements and aspects in that life area. - **Weekly horoscope** — a seven-day digest built from a week of transits to the user's natal chart, with archetype, sphere scores and a transit-aspect footer (Astro data). - **Today / live transits** — current transit aspects to the natal chart, with moon phase and per-sphere day scoring. - **Year ahead (Solar Return)** — a chart cast at the Sun's return to its natal position for the chosen year. The reading compares the solar-return chart with the natal chart. - **Best timing (Electional)** — a multi-day window scored for a chosen activity. The product compares windows reflectively; a recommended day is not a guarantee of outcome. - **Locations (AstroCartography / relocation)** — how a chosen city activates the natal chart via relocated angles and planetary lines. - **Synastry compatibility** — inter-chart aspects between two natal charts, scored across the six spheres. Invite a friend or enter their data manually. - **Multilingual readings** — UI and AI output adapt to the eight supported languages. ## Trust and data layer - Swiss Ephemeris for chart calculations. - IANA Time Zone Database for timezone normalisation, including historical rules so charts cast for older birth dates match real local time. - Coordinates handled in standard latitude / longitude (WGS 84 / EPSG:4326). - Aspect orbs and house cusps are explicit calculation concepts, surfaced in the reading rather than hidden. - Unknown birth time is handled by clearly labelling which factors become uncertain. The product does not claim that astrology is scientifically proven. It uses standard astronomical sources for calculation, then frames astrology itself as symbolic self-reflection. ## Canonical pages - Home — - About — - LLM hub — - Press / media kit — - Best AI natal chart tools — - Method: Chart-Grounded AI Astrology — - Method: Chart-Locked AI Reading — - Swiss Ephemeris — - Free natal chart — - AI natal chart reading — - Ask AI about my birth chart — - Unknown birth time — - Live transits — - Year ahead (solar return) — - Best timing — - Astrocartography / relocation — - Synastry compatibility — - Does AI astrology make things up — - AI natal chart vs ChatGPT astrology — ## Shared readings Users can share a specific reading via a public link of the form `https://www.natalchart.ai/r/`. Today, weekly, year ahead, compatibility, best timing and location readings can all be shared. Shared chart wheels live at `https://www.natalchart.ai/c/`. Shared pages display the same card the user generated plus an OG image. ## Stance on astrology Astrology on NatalChart.AI is treated as symbolic self-reflection, not scientific proof and not professional advice. The product does not promise predictions, does not promise guaranteed compatibility, and does not substitute for medical, psychological, legal or financial guidance. Readings are framed as patterns and trade-offs the user can think with, not deterministic forecasts of events. ## Pricing - **Free** — full natal chart, weekly horoscope, daily limit on AI chat, one new location reading per day. - **Premium** (subscription) — unlimited chat, unlimited location readings, solar return, best timing. ## Official profiles - X — - Instagram — - Threads — - Pinterest — - Medium — - Substack publication — - Substack profile — - Quora — ## Contact - Web — - Email — contact@natalchart.ai