Lowdown: How to Optimize Mediation for your App Part 1

Lowdown is a weekly series that brings you tips and tricks on how to best use AdMob to grow your app business, directly from members of the Google AdMob team.

A key goal for many app developers is to maximize revenue. If you monetize with multiple ad networks, you'll know that some have fluctuating CPMs and fill rates. AdMob mediation can help you determine the most valuable ad to serve in your app, and AdMob can help you determine which ads to serve. 

Today, we’re going to dive deeper into how our mediation platform works and introduce an optimization strategy that may increase your app’s revenue–enabling a feature called Live CPM. The best way to understand this feature is to first understand how basic mediation works.


AdMob is a robust mobile ads platform that includes mediation–allowing you to serve ad impressions from multiple 3rd party networks, your own house ads, and Google’s advertising inventory. With basic mediation, you’re required to rank all of the ad networks you use, assigning a predicted CPM for each one. When it’s time to serve an ad, the mediation platform will first make a request to the network you’ve ranked as number 1. If that network doesn’t serve an ad, it will make a request to your second-ranked network. It will continue down your list until an ad is served. Although helpful, this setup is unsophisticated. It doesn’t matter if network 2 or 3 is able to pay you a higher CPM, you’ve already committed yourself to the fixed ranking, and there’s a better way to increase revenue.

Lowdown: How to Optimize Mediation for your App Part 1

Mediation with Live CPM

In contrast, when the Live CPM feature is enabled, you increase your chances of higher CPMs with real time, dynamic competition. When it’s time to serve an ad in your app, Google’s advertising demand will provide its most valuable CPM, and compare this to the CPM you’ve assigned for your first-ranked network. Whichever network has a higher CPM will get the impression.

Lowdown: How to Optimize Mediation for your App Part 1 2

If your first-ranked network wins, but is unable to fill the impression, the process will repeat with the next-ranked network in your chain. This all happens in real time.

When enabling Live CPM, the initial results can be startling. Without it, you’re much more likely to miss your next network’s top tier demand. With it, your set-up is dynamic and top tier impressions from both AdMob and your other networks can be served. If you’d like to learn more, check out our case study on how Thapster, a smartphone music game app, succeeded with Live CPM and visit our Help Center to get more in-depth instructions on how to implement it.

In the next edition of Lowdown we’ll be looking at how you can further optimize Live CPM. Be sure to stay connected on all things AdMob by following our Twitter page.