What happens if you increase your PPC budget? Enter your current results (excluding branded campaigns) in the blue cells to find out. The calculator estimates the impact on revenue, conversions, CPA, and ROAS using the square root rule.

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Every next dollar of ad spend returns a little less than the one before it. That's diminishing returns. The square root rule puts a number on it: double your budget and your results increase by 1.41x, not 2x. Triple it, and you get about 1.73x.