Google’s mobile advertising network Admob added automatic conversion tracking yesterday to make it easier for developers to figure out whether their campaigns have actually produced downloads.

Before, app publishers would have to configure special code to see how their spending actually translated into downloads. Now all AdMob Android campaigns will automatically show conversion data from the Android Market. Inside Admob’s dashboard, there’s now a new section called App Conversion Tracking, that will show the number of downloads and the cost per download. Google didn’t say anything about conversion tracking for iOS.

As marketing costs have gone up over the past year, developers have told us they’ve struggled with finding the right balance between many different channels from install networks to display ads to free-app-a-day products. Many of the biggest game developers rely on using paid marketing to bring in users at a lower cost and then earn revenue through in-app purchases and advertising. They keep the split between spending on user acquisition and virtual currency revenues.