Google has launched a new feature for its Conversion Optimizer tool for AdWords. It’s called Target CPA Bidding, and lets advertisers set a bid that reflects the average amount they’d like to pay for a conversion, as opposed to the maximum they’re willing to pay for it.

"We launched Conversion Optimizer in 2007 as a tool to improve your campaign ROI," says Emily Williams of Google’s InsideAdWords crew. "Conversion Optimizer analyzes your conversion tracking data and automatically adjusts your bids for each auction. Over the past few years, we’ve been pleased to hear from a number of you that you’ve seen significant ROI improvements after implementing Conversion Optimizer. In fact, analysis indicates that, on average, those of you who use the tool experience a 21% increase in conversions along with a 14% decrease in CPA."

That analysis is based on Conversion Optimizer campaign performance over a year’s time, with a control set of campaigns.

"This latest update to Conversion Optimizer was made in response to your feedback," says Williams. "We’ve heard from many of you that you’re more accustomed to thinking in terms of a target or average CPA when it comes to managing your online advertising (as opposed to the Max CPA bids which the tool has historically required). We hope that having the additional Target CPA bidding option will make it even easier for you to boost your AdWords ROI."

To use the new Target CPA bidding feature, advertisers can go to the settings tab in their account, and go to "Focus on Conversions". From there, just click Advanced Options. Conversion Optimizer itself is only available for campaigns using conversion tracking, and have received at least 15 conversions over the last 30 days.