Calculation method
The selected reroll changes each die's success chance, then the tool recalculates the pool. It provides defined rules instead of claiming every custom reroll.
Assumptions and limits
This is a tabletop design scenario using your inputs, not a prediction of player experience. Check your game's exact rules and edge cases before finalizing a design.
Related tools
Define exactly what is rerolled
The initial success chance, number of dice, and reroll rule determine whether a reroll affects failures, every die, or a limited subset. Read the result as the probability after the stated reroll condition, not as a universal advantage value.
Use the result in a design decision
Compare one reroll with an extra die at the same target. They can feel different even when their success chances are similar because rerolls change a failed moment while extra dice change the initial pool.