Generic gacha math · user-supplied inputs

Featured Target Two-Stage Chance Calculator

Separate “get the rarity” from “the rarity is the target” in a transparent constant-rate two-stage model.

Quick answer

Example: A 0.6% top-rarity rate with a 50% featured share creates a 0.3% effective target rate before any changing-rate or guarantee mechanic is considered.

Effective target rate per pull —

Chance of at least one target —

Chance of any top-rarity result —

What this calculator does

A two-stage model first asks whether a pull reaches the selected rarity and then whether that rarity result is the featured target. Multiplying those two probabilities gives an effective per-pull target rate.

The calculator applies the standard at-least-one formula separately to the effective target rate and to the broader top-rarity rate. Seeing both numbers makes the gap created by the featured share explicit.

Guarantee states and changing pity rates are intentionally excluded. Enter this model only when constant independent stages are an appropriate description of the scenario you want to inspect.

Formula

effective target rate = rarity rate × featured share; session chance = 1 − (1 − effective rate) ^ pulls

Example: A 0.6% top-rarity rate with a 50% featured share creates a 0.3% effective target rate before any changing-rate or guarantee mechanic is considered.

FAQ

Why multiply the two percentages?

The target event requires both stages: reaching the rarity and then selecting the featured outcome within that rarity.

Can I use 100% for the featured share?

Yes. Then every entered top-rarity success is treated as the target.

Does this model a guaranteed next featured result?

No. Each pull is independent and uses the same two-stage rate.

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