How is the chance calculated?
If each roll is independent and has the same probability p = 1/N, the chance of at least one success in n rolls is 1 − (1 − p)^n. The 50%, 90% and 99% thresholds use that model. Actual game mechanics may differ.
Planet RNG Roll Odds Calculator
Choose a weapon and a roll count to explore a mathematical scenario. This calculator assumes independent rolls with a constant probability of 1/N. The displayed weapon rates come from historical gameplay readings; the assumption is not a confirmed description of Planet RNG's roll system.
Pick a target
The relationship between displayed rates, Luck, mutations and any pity system has not been confirmed. These results are model examples, not an account-specific forecast, a minimum chance or a guaranteed number of rolls.
Result
3.88e-9%
chance of seeing Entropy Well at least once in 100 rolls
- Average rolls needed
- 2,580,000,000,000
- Rolls for 50% confidence
- 1,788,319,725,845
- Rolls for 90% confidence
- 5,940,669,539,924
- Rolls for 99% confidence
- 11,881,339,079,847
This model assumes independent rolls with the same success chance each time. It does not establish the game's luck formula or whether a pity system applies. For rare outcomes, reaching the average gives about a 63% chance, not a guarantee. A count marked ≈ is rounded.
FAQ
Planet RNG Roll Odds Calculator FAQ
Does hitting the average number of rolls guarantee the item?
No. In this model the expected waiting time is N rolls. The chance by then is 1 − (1 − 1/N)^N: 75% for a 1-in-2 item, approaching 63.2% as N becomes large. Neither the average nor a 99% threshold guarantees a drop.
Why are some weapons missing from the picker?
Only entries with a numeric rate usable by the calculator appear. Some historical records have no readable rate, while others retain a printed suffix that has not been safely converted to a number. Those entries remain in the weapon database.