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Marketing math guides

Plain-English explanations of the formulas behind ads, affiliate and growth decisions - each one paired with a free calculator.

GuideWhat is a good ROAS?What counts as a good ROAS depends on your margin. Break-even ROAS by margin, typical ROAS by channel, and how to set a target ROAS that leaves profit.GuideBreak-even ROAS formulaThe break-even ROAS formula is 1 / gross margin. How to calculate gross margin correctly, worked examples, and how to turn break-even ROAS into CPA and bids.GuideHow to calculate EPCEPC = commissions / clicks. How to calculate earnings per click, EPC per 100 clicks, what a good EPC is, and how to use EPC to choose affiliate offers.GuideLTV to CAC ratioThe LTV:CAC ratio compares customer lifetime value to acquisition cost. Why 3:1 is the common target, how to calculate both sides correctly, and how to improve it.GuideHow long to run an A/B testHow long to run an A/B test: sample size by conversion rate and expected lift, why to run at least one to two weeks, and the mistakes that create false winners.