How to Use the Buff Stack Effect Calculator
The same buff can end up wildly different depending on how a game stacks it. Enter the per-stack effect and stack count, and this calculator compares the final stat increase across additive, multiplicative, and independent stacking rules.
Additive stacking simply sums the percentages and applies them once — common for buffs like attack power runes that stack intuitively. Multiplicative stacking re-multiplies the running total with every stack, so the increase grows exponentially as stacks build up.
Independent stacking is used for unrelated probability-based effects like critical hit or evasion, using the formula 1-(1-p)^n. This is the standard probability formula for the chance that at least one of several independently triggering effects succeeds.
Frequently Asked Questions
Additive stacking sums percentages and applies them once, while multiplicative stacking re-multiplies the running total on every stack. With the same per-stack value, multiplicative grows much faster as stacks increase.
It's used when stacking separate probability-based effects like critical hit, evasion, or resistance. The formula is 1-(1-p)^n, giving the combined chance that at least one effect triggers independently.