Work backward from unit economics and funnel conversion to maximum CPA, CPL, CPC, CPM and the ROAS floor that still leaves your target profit.
Model reviewed September 4, 2026 · Inputs stay in your browser
Decision model
The formula
Max CPA = expected pre-ad contribution − target profit. Max CPL, CPC and CPM cascade backward through lead-to-sale rate, click-to-lead rate and CTR.
This tool is designed to combine assumptions that are usually split across several simpler calculators. Every real-world rate is editable.
Enter your assumptions and calculate.
One ceiling across the funnel
Most ad calculators stop at one metric. This tool begins with actual order economics, calculates the maximum acquisition cost, then pushes that ceiling backward through the funnel into maximum CPL, CPC and CPM.
How to model ecommerce
For a direct ecommerce purchase, use the click-to-lead / purchase rate as your site conversion rate and set lead-to-sale to 100%. For lead generation, use both stages separately.
Returns matter before bidding
A campaign can look acceptable in the ad dashboard while returns erase contribution later. The expected-contribution step makes return/refund risk part of the bid ceiling before traffic is purchased.
Why this calculator exists
There are many good single-formula calculators. This one is intentionally more complex: it helps answer a decision where several risks and costs interact. Complexity is useful only when the extra inputs change what you would do.
Spreadsheet version
Want to save or modify this model?
Use the matching Paid Ads Profit Ceiling Google Sheets template to keep scenarios, change assumptions or extend the model.