Ad Budget Calculator
Find the ad budget you need to hit a conversion target at a given CPA. Enter any two values and the calculator solves the third - budget, target conversions, or target CPA.
How ad budget is calculated from conversions and CPA
Budget = Target conversions x Target CPAIf you know how many conversions you need and what each conversion is worth paying for (your target CPA), multiplying them gives you the required budget. This is the planning direction most performance marketers use: set a conversion goal first, then work backwards to the spend required.
Target CPA should be derived from your conversion value and margins - not from platform recommendations, which optimize for volume, not profitability. Use the CPA Calculator or Break-even ROAS Calculator to find a defensible CPA target before entering it here.
This is a linear estimate. In practice, CPA tends to rise as you increase budget (diminishing returns), so treat the output as a floor estimate, especially for large budget jumps.
- Required budget
- Total ad spend needed to hit the target at the given CPA.
- Target conversions
- The number of goal completions you want the campaign to deliver.
- Target CPA
- The maximum you are willing to pay per conversion to remain profitable.
Common questions
How do I set a target CPA?
Start from conversion value. If a customer is worth $200 and you want a 30% margin after ads, your target CPA is $140. Use the Break-even ROAS Calculator to derive a CPA that is consistent with your gross margin.
What if I do not know my conversion volume target?
Work backwards from revenue: divide your revenue target by the average order value to get the number of conversions needed. Enter that here with your target CPA to get the required budget.
Why does actual spend sometimes differ from the calculated budget?
Campaigns rarely deliver exactly at the target CPA. Budget pacing, auction competition, and audience availability all cause variation. Build a 10-20% buffer into budgets for campaign optimization room.