Is the calculator exact?

The calculator is a starter decision helper. Add formulas, tables, and game-specific inputs when exact rates are available.

Primary tool

Grand Blue Reroll Calculator

Choose a local player-input tool for reroll probability, route decisions, or boss preparation. No disputed Grand Blue rate is inserted as a default.

OPEN TOOL

Reroll probability

Bring your own verified rate and calculate independent-roll odds.

OPEN TOOL

Route planner

Use level, island, and story readiness to choose a safer next step.

OPEN TOOL

Boss run planner

Build a preparation checklist and track your own attempts.

YOU PROVIDE THE RATE

Calculate the chance of at least one target roll

Grand Blue race and trait odds are disputed or incomplete, so this tool never inserts one for you. Enter only a rate shown by a source you trust.

Chance per independent roll (%)Number of rolls

Enter a per-roll percentage to calculate. Reported Grand Blue odds are intentionally not prefilled.

Formula: 1 − (1 − p)ⁿ. It assumes every roll is independent and uses the same probability. Conditional variants need the combined rate, not two percentages added together.