A 4-step health check for your target ROAS and CPA

Target ROAS and CPA aren’t optimization settings. They’re business decisions.

Many accounts inherit a target from a previous agency, finance team, or account manager without questioning whether it still makes sense. Set it too aggressively, and you limit volume and lose auctions. Set it too loosely, and you sacrifice profit.

This four-step framework shows you how to calculate a defensible target, test whether it’s realistic, and confirm that your last advertising dollar is still making you money.

Why your target matters more than you think

Two companies sell the same product. One tells their agency to hold ROAS at 800%. The other is fine with 400% because they’d rather take market share than protect margin. Guess who wins more auctions, shows up more often, and slowly takes the category.

As my high school economics teacher would have said, ceteris paribus, the advertiser with the more aggressive target wins. In other words, all else being equal, including conversion rate and Quality Score. In real life, ceteris is rarely paribus. But for this example, we’ll pretend it is.

The first company isn’t being disciplined. It’s being outbid, and it probably doesn’t know it. Somewhere, a target was set, entered into Smart Bidding, and never questioned again.

That doesn’t make the second company the smart one, by the way. Trading margin for market share can be brilliant or reckless, depending on the business behind it. The difference between these two companies isn’t who has the lower target. It’s whether anyone chose it on purpose.

This is the quiet problem with target ROAS and CPA. Most practitioners treat the number as a given. It came from the client, finance, or whatever the account was doing when they inherited it. It rarely came from a calculation they were involved in.

Now that most campaigns use a bid strategy based on target CPA or ROAS, that target is the main lever you still control. Get it wrong in either direction, and you’ll either leave growth on the table or quietly lose money on every sale.

The good news is that the right target isn’t a matter of opinion. You can calculate it two ways:

• From the inside out, starting with your profit margin and how much of it you’re willing to spend to grow.
• From the outside in, sanity-checking against what the auction and your current performance will actually allow.

Once you have your number, there’s one final check most accounts never run: whether your last dollar is still making you money. None of it requires more than arithmetic, and all of it should feed one conversation you ought to have at least once a year with whoever owns the number.

I’ll share every formula along the way so you can rebuild them in a spreadsheet and run your own numbers before you finish reading.