Grahlok
How accurate is Grahlok?
Last checked 8 October 2026
A kundli is only as good as the astronomy under it. Grahlok calculates every chart on your phone, and we test those calculations against the Swiss Ephemeris, the reference library that professional astrology software is built on. Here is what we measured.
What we test
| Calculation | Reference | Worst error found |
|---|---|---|
| Sun, Mercury, Venus, Mars, Jupiter, Saturn | Swiss Ephemeris | 0.9″ (arcseconds) |
| Moon | Swiss Ephemeris | 4.2″ |
| Rahu and Ketu (mean node) | Swiss Ephemeris | 0.1″ |
| Lahiri ayanamsa | Swiss Ephemeris | 0.001″ |
| Ascendant (lagna) | Swiss Ephemeris | 4.5″, including births near the Arctic Circle |
| Sunrise and sunset | Swiss Ephemeris | under 1 second |
| Tithi, nakshatra, yoga and karana end times | Swiss Ephemeris | 3.9 seconds (usually under 1 second) |
| Divisional charts (D1–D60), ashtakavarga | PyJHora | exact match |
| Vimshottari dasha dates | PyJHora | exact match |
One arcsecond is 1/3600 of a degree. The Moon moves about one arcsecond every two seconds, so these errors are far smaller than the uncertainty in any recorded birth time.
A real day, side by side
Panchang for Ahmedabad, Thursday 8 October 2026, in IST:
| Ends at | Grahlok | Swiss Ephemeris | Drik Panchang |
|---|---|---|---|
| Krishna Trayodashi (tithi) | 22:16:29 | 22:16:30 | 22:15 |
| Purva Phalguni (nakshatra) | 21:20:24 | 21:20:24 | 21:20 |
| Shukla (yoga) | 00:58:28 | 00:58:29 | 00:58 |
| Garaja (karana) | 10:44:26 | 10:44:26 | 10:43 |
Different panchangs can disagree by a minute or two because they use slightly different conventions for the ayanamsa and the Moon. Drik Panchang shows whole minutes. Grahlok follows the Swiss Ephemeris with the standard Lahiri ayanamsa, and shows times to the second.
The details that usually go wrong
- Old Indian clock times. Before IST was used everywhere, Bombay kept its own time until 1955 and Calcutta until 1948, and India ran on War Time (+6:30) in 1942–45. Grahlok applies these rules, so a 1950 Mumbai birth is not an hour off.
- Your choice of system. Advanced settings offer 6 ayanamsas (Lahiri, Drik-style Lahiri, Raman, KP, True Chitra and Yukteshwar), mean or true node, several house systems, and North, South or East Indian charts.
- Matching. Both North Indian Ashtakoota (36 gunas) and South Indian 10 porutham.
Check it yourself
Pick any birth chart in the app, open Kundli → More → Expert details to see degrees to the second, and compare with your preferred software set to Lahiri ayanamsa. If something doesn't match, email support@grahlok.com with the birth details and we'll look into it.
Accurate astronomy doesn't make astrology a science. Readings are guidance, not a substitute for medical, legal or financial advice.