Read November 13, 2026 · Shymea is ours
The best birth chart apps, and what they calculate with
Seven apps compared only on what each company states: ephemeris, house systems, horary, astrocartography, platforms and price. No ratings, no scores, and no accuracy claims we didn't measure.
Photo: Sarah Pflug / Burst
Which birth chart app is the most accurate?
There is no public, independent accuracy test of astrology apps, so this page compares what each app says it calculates with. Astro Gold names the Swiss Ephemeris; Co-Star says it uses NASA data; Shymea (ours) computes with NASA JPL's DE442 and publishes a test of 870 positions against the Swiss Ephemeris, with a median difference of 0.17 arcseconds. CHANI, The Pattern, TimePassages and Sanctuary don't name a source on the pages we checked. For a serious chart, Astro Gold and TimePassages are the established tools; Shymea adds horary and astrocartography in one app.
At a glance
Three of the seven name a calculation source: Astro Gold (Swiss Ephemeris), Co-Star (NASA data) and Shymea (JPL DE442, ours). No one has published an independent test of all of them.
- Name a source
- 3 of 7Astro Gold, Co-Star, Shymea
- Several house systems
- Astro Gold, TimePassagesCHANI uses Whole Sign
- Astrocartography
- Astro Gold, ShymeaAstro Gold as an add-on
- Shymea vs Swiss Ephemeris
- 0.17″ median870 positions, 1900–2035
Get your free birth chartOurs, computed on JPL DE442. No account.
Accuracy
Why the ephemeris matters less than you'd think
Try this today
- Enter the same birth time and place in two apps and compare the Sun's degree first. If it matches, look at the house system next.
- If your rising sign differs between apps, check the birth time and the time zone before anything else.
Any app built on a modern ephemeris, such as JPL's DE series or the Swiss Ephemeris (which is itself derived from JPL data), will put your planets within a fraction of an arcminute of each other. In our own test the largest gap between the two over 870 positions was under 27 arcseconds, for the Moon, less than 2% of the Moon's own width in the sky.
When two apps disagree about your chart, the cause is almost always something else: a different house system (CHANI says it uses Whole Sign houses; Shymea's calculators use Placidus), a rounded or wrong birth time, a wrong time zone for an older birth, or a different formula, for example a Part of Fortune that ignores day and night births. Check those first.
Picks
Which app for which person
Astro Gold is the pick if you want a professional chart tool: its listing names the Swiss Ephemeris, its FAQ lists many house systems, and astrocartography is an add-on. It does not explain the chart in conversation.
TimePassages suits learners who want readings written by astrologers, which its listing says are not AI. Its site says one login works on iPhone, Android and the web.
CHANI is a calm daily practice built on Whole Sign houses, with audio and written readings by its astrologers.
Co-Star and The Pattern are social and personality-led; they say little about how they calculate.
Sanctuary centres on paid live readings; its listing describes an interactive birth chart of the Sun, Moon and rising sign.
Shymea (ours) is for people who want the chart computed carefully and then explained: it shows the placements behind each answer, and it includes horary questions and astrocartography. It is new, and it uses AI to write the explanations.
More to read
One shorter read. It opens in place.
Method
What we compared, and what we didn't
On 13 November 2026 we read each app's US App Store listing and its own website, and recorded only what those pages state: platforms, price model, the ephemeris or data source if one is named, house systems, horary and astrocartography, and who writes the readings. Every claim links to its source below.
Continue readingShow less
We did not measure any competitor's positions. Doing that fairly would mean entering the same births into every app and reading the degrees off each screen, and we haven't done it. The only accuracy figures on this page are for our own engine, from our published comparison with a downloadable table.
Shymea publishes this page and Shymea is one of the apps compared. Read it with that in mind.
What each app states
Read on November 13, 2026 from each company's own website and its US App Store listing; "Not stated" means none of the pages we read says it. Prices are US App Store prices unless marked. We did not test any competitor's positions.
| App | Ephemeris or data source | House systems | Who writes the readings |
|---|---|---|---|
| Astro Gold | Swiss Ephemeris ("Powered by the highly accurate Swiss Ephemeris") | Many; FAQ lists Placidus, Koch, Porphyry, Whole Sign and others | Not stated |
| TimePassages | Not stated | A choice ("Change house calculations"); systems not named | Astrologers, "Not AI" (listing) |
| CHANI | Not stated | Whole Sign houses (its own article) | Chani Nicholas and its team of astrologers, "not AI" (listing) |
| Co-Star | "NASA data" (listing) | Not stated | "Real human astrologers who collaborate with AI technology" (listing) |
| The Pattern | Not stated | Not stated | Not stated |
| Sanctuary | Not stated | Not stated | Live readings by "professional astrologers, tarot readers, and psychics"; horoscope authorship not stated |
| Shymea (ours) | NASA JPL DE442 via Skyfield; tested against the Swiss Ephemeris (870 positions, median gap 0.17 arcseconds) | Placidus on the web calculators | AI explanations of computed placements, which it shows |
| App | Horary (question) astrology | Astrocartography |
|---|---|---|
| Astro Gold | Not stated | Yes, Astro Mapping add-on ($24.99); not on Android per its comparison table |
| TimePassages | Not stated | Not stated |
| CHANI | Not stated | Not stated |
| Co-Star | Not stated | Not stated |
| The Pattern | Not stated | Not stated |
| Sanctuary | Not stated | Not stated |
| Shymea (ours) | Yes (listing) | Yes (listing) |
| App | Platforms | Price model |
|---|---|---|
| Astro Gold | iPhone, iPad, Mac; separate Android and Windows versions on its site | Free; Gold $7.99 a month or $39.99 a year, or a $69.99 lifetime unlock (prices on its site) |
| TimePassages | iPhone, Android and web with one login; desktop for Windows and macOS | Free; Pro $7.99 a month or $59.99 a year; single charts $0.99 |
| CHANI | iPhone and iPad; Android (store button on its site) | Free; subscription $11.99 a month or $107.99 a year |
| Co-Star | iPhone (App Store listing); other platforms not checked, its site blocked our reader | Free; Pro-Star $8.99 a month; one-off reports and question packs |
| The Pattern | iPhone; Android (store link on its site) | Free; Go Deeper+ $14.99 a month or $83.99 a year |
| Sanctuary | iPhone; Android (store button on its site) | Free; Sanctuary+ $14.99 a month or $49.99 a year; paid live readings |
| Shymea (ours) | iPhone; free calculators on shymea.com | Free; Premium $9.99 a month or $89.99 a year; horary packs and reports one-off |
| Body | Largest difference (″) |
|---|---|
| Moon | 26.73 |
| Mercury | 3.28 |
| Venus | 2.09 |
| Sun | 1.80 |
| Mars | 1.40 |
| Pluto | 0.77 |
| Neptune | 0.75 |
| Jupiter | 0.69 |
| Saturn | 0.42 |
| Uranus | 0.34 |
| Feature | Astro Gold | TimePassages | CHANI | Co-Star | The Pattern | Sanctuary | Shymea (ours) |
|---|---|---|---|---|---|---|---|
| Daily horoscope | Not listed | Yes | Yes | Yes | Not listed | Yes | Yes |
| Full birth chart readings | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Transits and timing | Yes | Yes | Yes | Not listed | Yes | Not listed | Yes |
| Compatibility with friends or partners | Yes | Yes | Not listed | Yes | Yes | Yes | Yes |
| Progressions, composite or solar arc charts | Yes | Yes | Not listed | Not listed | Not listed | Not listed | Yes |
| Ask your own questions | Not listed | Not listed | Not listed | Yes | Yes | Not listed | Yes |
| Meditations, podcasts or audio | Not listed | Not listed | Yes | Not listed | Yes | Not listed | Not listed |
| Horary (question) astrology | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Yes |
| Astrocartography and relocation | Yes | Not listed | Not listed | Not listed | Not listed | Not listed | Yes |
| Live human readers or advisors | Not listed | Not listed | Not listed | Not listed | Not listed | Yes | Not listed |
| App | Monthly | Yearly | Other purchases |
|---|---|---|---|
| Astro Gold | $7.99 | No yearly plan shown ($95.88 at monthly) | Free to download with a 7-day trial. Gold Monthly $7.99 (a lifetime upgrade is mentioned in the description; its price is not among the purchases shown). Reports $2.99 to $3.99. Astrolocality Maps $24.99. |
| TimePassages | $7.99 | $59.99 | Free to download. Pro $7.99 a month or $59.99 a year. Single charts $0.99 each (birth, comparison, transit, progressed, solar arc). |
| CHANI | $11.99 | $107.99 | Free to download. Subscription $11.99 a month or $107.99 a year. A monthly plan with a trial is also listed. |
| Co-Star | $8.99 | No yearly plan shown ($107.88 at monthly) | Free to download. Pro-Star $8.99 a month. Questions $2.99 (5), $4.99 (10), $6.99 (25). Your Year Ahead $11.99. Advanced Chart (Self or Relationships) $8.99 each. Eros $6.99. |
| The Pattern | $14.99 | $83.99 | Free to download. Go Deeper+ $14.99 a month, $29.99 a quarter or $83.99 a year. Connect+ $24.99 a quarter. Extra profile slots $9.99 to $19.99. |
| Sanctuary | $14.99 | $49.99 | Free to download. Sanctuary+ $14.99 a month or $49.99 a year. Intro readings $4.99; 10-minute readings $29.99 (tarot) or $49.99 (psychic). |
| Shymea (ours) | $9.99 | $89.99 | Free to download. Premium $9.99 a month or $89.99 a year (shymea.com/pricing/). Horary packs $1.99 (3) or $4.99 (10). Reports from $3.99. |
All times are UTC. In the Americas the local date can be a day earlier; in Asia and Australia a day later.
Quick answers
Which birth chart app is the most accurate?
No independent test has compared them. Apps that use a modern ephemeris (JPL DE or Swiss Ephemeris) agree on planet positions to well under an arcminute. Astro Gold names the Swiss Ephemeris, Co-Star says it uses NASA data, and Shymea uses JPL DE442 and publishes its own comparison. The others don't name a source on the pages we checked.
Why do two apps give me a different rising sign?
Almost always because of the birth time, the time zone or the house system, not the ephemeris. The rising sign changes about every two hours on average, so a rounded time near a sign change can flip it.
Which app lets me choose my house system?
Astro Gold's FAQ lists Placidus, Koch, Porphyry, Whole Sign and others, and TimePassages' site says you can change the house calculation. CHANI says it uses Whole Sign houses. Shymea's calculators use Placidus.
Which apps offer astrocartography?
Of the seven compared, Astro Gold (as a paid add-on) and Shymea list astrocartography. For horary, Shymea's is the only listing of the seven that describes it.
Is this comparison independent?
No. Shymea publishes it and Shymea is one of the apps compared. We kept to facts each company states itself, linked every source, and did not rate or score anyone.
