Fill rate tells you how many of your ad opportunities actually turned into ads. It measures how well a sales team or ad network monetizes the space a site makes available.
Why fill rate matters
A 100 percent fill rate means an ad appeared every time there was a chance to show one. Anything less means lost income: a page loaded but at least one ad slot stayed empty. That happens for two main reasons:
- Lack of demand. No direct deal or network has an ad for that slot, country or audience.
- Technical problems. Slow ad code, wrong sizes or a poor set-up.
Most networks should fill nearly all requests. If one struggles to find demand for your impressions, try another.
Fill rate vs coverage
In AdSense the same idea is called coverage. If a page has three ad units, it makes three ad requests. If two show ads and one stays blank, coverage is 67 percent.
How to raise fill rate
- Use mediation or header bidding so unfilled requests go to the next buyer.
- Offer standard sizes that most advertisers have creatives for.
- Add a backfill network or house ads for the remaining slots.
- Check fill rate by country: weak countries often need a specialist network.
Niche demand fills niche inventory
Low fill is common on sports, poker and betting pages, because mainstream networks restrict gambling-related content and many brand advertisers avoid it. The fix is to add buyers who want exactly that audience: gambling ad networks and casino or sportsbook affiliate offers. They often turn a half-empty slot into the best-paying placement on the page. See gambling ad networks for publishers.
