Astrology Software Accuracy: A Seven-Point Checklist Before You Trust a Chart

Two calculators can disagree by an entire nakshatra pada while both claim to be correct. The difference is almost never the planets themselves; it is the inputs and settings. Before you trust any chart, from Astrometry or anywhere else, run this seven-point checklist.

1. Birth data quality

Everything downstream depends on the recorded birth time. A hospital record is stronger than family memory, and family memory is stronger than a guess. If the time is uncertain by more than a few minutes, read our birth time rectification checklist before interpreting sensitive factors like the ascendant or divisional charts.

2. Time zone and daylight saving

The single most common error in manual data entry is the wrong UTC offset. India has used UTC+5:30 continuously since 1947, but many other countries have changed offsets and observed daylight saving at different times. Always confirm the offset the software applied, not just the city name. Good tools display the offset next to the birth details so you can verify it.

3. Coordinates

Latitude affects house cusps and the ascendant; longitude shifts local sunrise-based periods. A software that silently uses a state capital for every city in that state introduces real error. Astrometry resolves named places to their own coordinates and shows the values used, so you can check them against a map.

4. Ayanamsa

Vedic astrology measures positions against the fixed stars, and the conversion from tropical positions uses an ayanamsa. Lahiri is the most common in India, but KP work traditionally uses the KP ayanamsa, and the difference between systems is currently around 24 arc-minutes. If you compare two programs, confirm both use the same ayanamsa before comparing anything else.

5. House system

Whole sign, equal, Sripati and Placidus houses can place a planet in different bhavas. Neither is 'wrong'; they answer different questions. What matters is that you know which system produced the chart you are reading. Our Nadi/KP software uses the KP (Placidus-based) cuspal system, while the Kundli tool follows the whole-sign convention of classical Parashari work.

6. Rounding and display precision

A Moon displayed to the nearest degree hides up to half a degree of motion, which is about an hour of time. For dasha balance and divisional charts, insist on at least arc-minute precision in the underlying calculation, even if the display is rounded.

7. Reproducibility

The final test: enter the same data twice and confirm you get the same chart, and re-open a saved report and confirm it matches the original. Deterministic, local calculation, which is how every Astrometry engine works, makes this check trivially pass. If a tool gives different answers on different days for the same birth data, find out why before trusting either answer.

Putting it together

Accuracy is a chain, and the weakest link is usually an input, not the mathematics. Spend five minutes on this checklist and most 'my software disagrees' mysteries resolve themselves. For a worked example of how settings change results, see why Vimshottari Dasha dates differ between calculators.