Spend and funnel
Customer economics
Result
Customer acquisition cost (CAC)
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Above this cost per customer, advertising goes into the red
Below 3 the model usually cannot carry the rest of the costs
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This calculation is for informational purposes only and does not replace advice from a qualified professional. Formulas and rates may not fit your exact situation — double-check the figures before making decisions.
How it is calculated
The funnel is calculated top down: CPC = spend ÷ clicks, CPL = spend ÷ leads, CAC = spend ÷ sales. CAC is the key figure — what one paying customer costs — and it is what you compare against what the customer brings.
Gross profit per customer = average order value × margin ÷ 100. LTV = gross profit × lifetime purchases. Measuring payback on revenue instead of profit is the most common mistake: a campaign showing 300% return on revenue can still lose money at a 20% margin.
ROMI = (gross profit − ad spend) ÷ ad spend × 100%. Zero means the campaign broke even on gross profit; covering fixed costs as well needs a buffer on top. Ad cost ratio = spend ÷ revenue × 100% is the same picture from the other side, more familiar in e-commerce.
Maximum CAC = gross profit per customer × lifetime purchases, which is LTV. While the actual CAC stays below it, scaling makes sense; once they meet, extra volume only adds losses.