Read the odds, not the hype.

A 4.4% rarity rate does not mean you are guaranteed a success in 23 rolls—and it does not describe your exact target Stand.

Three different questions

Per-roll chance describes one attempt. Cumulative chance asks whether at least one success occurs across several attempts. Expected attempts is an average over repeated experiments, not a deadline for your own result.

The model we use

For independent rolls with a constant success probability p, the probability of no successes in n trials is (1 − p)ⁿ. Subtract it from one to get the probability of at least one. A changing pool or exclusion rule can make that simple model inaccurate.

What is deliberately missing

We do not turn a rarity probability into a per-Stand probability by dividing by a roster count. That would assume equal weighting and current availability without evidence. We also do not infer normal-arrow rates from rounded upgrade rates.

Keep the source and its date

Our presets are community-reported figures, not independently sampled results. When the game changes, the dataset and assumptions need review. Use the custom input for mathematics, not to create a new “official” number.