Conversion Optimizer - Max CPA vs Target CPA

conversion optimizer max target cpa

[brewno]

I've seen this argued before, but I'm wondering if anyone has some new thoughts on the topic:

If the goal is maximizing conversions, what is the best Conversion Optimizer setting - Max CPA or Target CPA?

In my specific case, my target CPA is $75 account wide, though I'm considering turning on conversion optimizer for a high volume/high cost campaign (historical CPA ~$130). I'll make up my account-wide averages on branded campaigns, etc.

I'm torn between setting a Max CPA of $150, or a target CPA of $125. I'm not too concerned with where the actual CPA for this campaign ends up, as long as it is under ~$150. I would much rather max out conversion total numbers.
- any advice, experience, etc welcome.

[brewno]

also, has anyone noted a direct impact on Impression Share numbers when enabling Conversion Optimizer for the first time?

[Channel01]

They're both a means to an end so each can achieve your goal. You're basically telling Google to bid roughly the same in both of those scenarios that you outlined.

I've always used Max CPAs (Target CPA just became an option in the past year) but an argument can be made that there's less guesswork involved with the Target CPA approach. I haven't had any issues with the Max CPA targets though so I've never switched things up.

Regarding your Impression Share question, I've seen examples where volume can spike pretty dramatically at first when the Optimizer is turned on. It really depends on what your situation is though (e.g. how high your CPA bid is relative to the historical CPA performance, how long you've had conversion tracking running, etc). You can also see a big volume boost if you have certain keywords bid low that have the potential for more volume. If there isn't conversion history to prove otherwise, Google will bid them up to test out how they perform with more exposure. So those first few days may produce some odd traffic patterns but things should ultimately level out as the system responds to the conversion data it's seeing.