Understanding your maximum cost per acquisition (CPA) is one of the most important decisions in digital marketing and ecommerce. This calculator helps you determine the highest amount you can spend to acquire a customer while still breaking even based on your average order value (AOV) and gross margin.
Whether you're running paid ads on Google, Facebook, or marketplaces like Amazon, knowing your break-even CPA allows you to scale confidently, avoid overspending, and improve profitability. Instead of guessing or relying on rough estimates, this tool gives you a precise figure you can use to guide campaign optimisation and budget allocation.
The result shows the maximum amount you can spend to acquire a customer without making a loss. If your CPA exceeds this value, your business loses money on each sale before considering fixed costs.
The formula is simple:
Max CPA = Average Order Value × Gross Margin
Gross margin represents the percentage of revenue remaining after product costs. By multiplying this by your AOV, you determine how much profit is available to cover marketing costs.
Max CPA is a critical metric for scaling paid advertising. If your campaigns are operating below this threshold, you can increase spend to drive growth. If they exceed it, you need to optimise conversion rates, increase prices, or reduce costs.
Don’t just aim to break even. Set your target CPA 20–40% below your maximum to ensure consistent profitability and buffer against fluctuating ad performance.
Example 1: AOV £60, margin 40% → Max CPA £24
Example 2: AOV £25, margin 30% → Max CPA £7.50