What is Fill Rate?
Fill Rate measures the percentage of ad requests from a publisher's app that are successfully filled with an advertisement. When a user opens your app and triggers an ad request, the ad network may or may not have an ad available to serve. Fill rate tells you how often ads are actually delivered.
Fill Rate Formula
Example: 85,000 ads served ÷ 100,000 requests = 85% fill rate
Why Fill Rate Matters
Revenue Maximization: Every unfilled request is lost revenue opportunity. A 10% increase in fill rate can mean 10% more ad revenue.
User Experience: Low fill rates can create inconsistent experiences where ads sometimes appear and sometimes don't.
Network Evaluation: Fill rate helps you compare ad network performance and identify the best partners for your inventory.
Factors Affecting Fill Rate
Geography: Tier-1 countries typically have higher fill rates due to more advertiser demand. Tier-3 regions may see lower fill.
Ad Format: Banner ads usually have higher fill rates than video or rewarded ads due to lower creative requirements.
Time of Day: Fill rates often drop during off-peak hours when advertiser demand is lower.
User Demographics: Some user segments are more valuable to advertisers, leading to higher fill rates for those audiences.
Floor Prices: Setting high eCPM floors can reduce fill rate as fewer ads meet your price requirements.
💡 Pro Tip
Don't chase 100% fill rate at the expense of eCPM. Use waterfall or bidding strategies to maximize total revenue, not just fill rate. Sometimes accepting a lower fill rate with higher-paying ads generates more revenue.
How to Improve Fill Rate
Use Multiple Networks: Implement a waterfall or mediation strategy with multiple ad sources to catch unfilled requests.
Implement Bidding: Real-time bidding lets multiple networks compete simultaneously, improving fill.
Adjust Floor Prices: Lower your eCPM floors strategically for underperforming regions or times.
Optimize Placements: Some ad placements may have better fill than others based on viewability and engagement.