The exact model
A dynamic program follows pity from 0 to 69 and whether a ten-pull has already hit four-star or better. Ordinary five-star probability is 1.5%. On the last pull of a ten-pull without any earlier four- or five-star, the conditional five-star probability is 18.75%. Pity at 69 overrides that rule with a guaranteed five-star.
What the result means
Enter pulls since your last five-star in the selected region, and either a number of singles or ten-pull batches. The result is the probability of receiving at least one five-star, not an expected count or a species guarantee. A region without a five-star pool would require the source’s adjacent-rarity fallback; all current regional pools are checked before the model is used.
Shiny estimate boundary
For eligible independent shiny checks the probability is 1 − 0.99^n. This is a base-check comparison only. Sprite eligibility and the duplicate-rerouting rule mean it does not estimate the probability of a new shiny for your collection.
Check the calculator with known cases
Pity 0, singles, count 0 → 0%. Pity 0, singles, count 10 → 14.026956%. Pity 0, ten-pull batches, count 1 → 22.171739%. Pity 69, singles, count 1 → 100%. Blank, fractional and out-of-range inputs return a validation message instead of a made-up result.