Work out gacha pull probability instantly with clear inputs, formula shown and shareable results.
Without pity the chance is one minus the miss rate raised to the number of pulls; a hard pity counter guarantees the item once the threshold is reached, capping the worst case. At a 0.6% base rate ninety pulls only gives about a 42% natural chance, so the pity counter rather than the advertised rate is doing most of the work.
Base chance
P = 1 - (1 - rate) ^ pulls, capped at the pity threshold
Expected pulls
expected = minimum of pity threshold and 1 / rate
P = 1 - (1 - rate) ^ pulls, capped at the pity threshold. Without pity the chance is one minus the miss rate raised to the number of pulls; a hard pity counter guarantees the item once the threshold is reached, capping the worst case.
At a 0.6% base rate ninety pulls only gives about a 42% natural chance, so the pity counter rather than the advertised rate is doing most of the work.
Enter base rate per pull, pulls you plan to make, guaranteed pull at, cost per pull. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.