Google has decided to remove Max CPA as a bidding option from their Conversion Optimizer tool in AdWords:
In the coming months, we’ll be removing the ability to set a maximum cost-per-acquisition (max CPA) bid in a campaign using Conversion Optimizer. Soon after, we’ll begin to automatically switch campaigns that are still using max CPA bidding to target cost-per-acquisition (target CPA) bidding. If you’re using a max CPA bid, we recommend switching to a target CPA bid or the target return on spend (ROAS) flexible bid strategy.
If you’re like most of us, you were probably reasonably confused as to how Target CPA and Max CPA differed in the first place. Let’s go through what the differences were and why this change is actually a good one.
The max CPA option allowed advertisers to set a maximum price they were willing to pay for any single conversion.
A maximum CPA bid (max. CPA bid) is the most you’re willing to pay for each conversion, such as a purchase or sign-up. When you use Conversion Optimizer, most of your bids will be below whatever maximum you set.
This option can end up capping off conversion volumes if you’re not careful. If you set a max CPA below the historical CPA the predictive models will have a hard time reconciling your request against the historical signals used to capture conversions at your max CPA.
If your top converting keywords are converting above the maximum CPA you’ve set, then those conversions are no longer desirable because they are outside of the max CPA. This is why you may see a slowdown in conversions when you initially enable conversion optimizer using the max CPA bidding model.
Target CPA is a bit more flexible. Instead of giving Google a set price to stay below; you are setting a goal for the system to optimize toward.
A target CPA bid is the average amount you’d like to pay for a conversion. Some bids will be above this target and some will be below it, but altogether, the cost per conversion should average to the Target CPA you set.
I actually prefer this setting so that I don’t have to manually look out for conversions that are hitting above my max CPA. The system will include those in the predictive models used to dial things down to hit your target CPA. This means I’m not sacrificing conversions in favor of a maximum CPA and I’m less likely to be capped on volume.
The flexibility built into target CPA is also why you will see a variance in CPA as the tool works to optimize to your target. Some conversions will have a higher than desirable CPA, others will have lower. But in the end, your overall CPA should be at your target CPA goal. If the CPA is above your target on any given 30-day snapshot, it may be due to an inconsistency in your target vs. your history or due to low conversion volumes that may be throwing off the predictive modeling.
What Does The Change Mean?
Google will be moving your campaigns to target CPA from max CPA unless you take care of this first. If Google automatically updates your account, you may end up with inflated costs and CPAs if your campaigns were running on max CPA and that max is set higher than you’d like to actualize in order to account for outlier conversions.
If you’re already on target CPA, you won’t see any changes at all.
I highly recommend checking out your conversion optimizer settings and making any needed changes to your campaigns before Google sweeps through and makes those changes for you.