Learn & Understand

When 20% Plus 20% Isn't 40%: Stacking Math

Stack three twenty-percent damage buffs and you might expect a sixty-percent boost. Depending on the game, you could get exactly that — or seventy-three percent, or something else entirely. The difference comes down to whether bonuses add or multiply, a distinction that quietly makes or breaks character builds.

Two Ways to Combine

Percentage bonuses can stack two ways. Additive stacking sums them: three twenty-percent buffs give a flat sixty percent. Multiplicative stacking applies each in turn to the running total, so each buff boosts an already-boosted number. The two methods give different results, and which one a game uses shapes how powerful stacked bonuses become.

The Multiplicative Surprise

Under multiplicative stacking, each buff multiplies the previous total, so the bonuses compound. Three twenty-percent buffs multiply to about a seventy-three percent increase, not sixty — because the second buff boosts the first's boost, and the third boosts that. The more buffs stacked, the wider the gap between what addition predicts and what multiplication delivers.

Why It Matters for Builds

This distinction is the heart of build optimization. Under multiplicative stacking, combining many separate bonuses yields explosive, compounding power — the basis of the wildest high-damage builds. Under additive stacking, bonuses grow more modestly and predictably. Knowing which rule a game uses tells a player whether stacking more buffs snowballs or merely adds up.

Designers Use Both

Games often mix the two rules deliberately, adding bonuses within a category and multiplying across categories, to control how much power stacking can produce. Additive stacking keeps growth in check; multiplicative stacking allows dramatic scaling for those who assemble the right combination. The choice is a balancing tool, and reading the game's actual rules is essential before trusting a build's numbers.

Calculating the Stack

To compute a multiplicative buff total, use the Multiplicative Buff Stacking Calculator. Apply the result to output with the DPS Calculator, and compare builds with the Critical Hit Expected Damage Calculator.