- Formula
- Filled ad requests / total ad requests
- Unit
- %
- Models
- Media
| Tier-1 traffic | 85%–95% | AdReact 2026; Appodeal |
| mixed global | 70%–85% | AdReact 2026; Appodeal |
| emerging market | 50%–70% | AdReact 2026; Appodeal |
What it is
Fill rate measures the percentage of ad requests that are successfully matched with and served an ad. Defined as: filled ad requests / total ad requests.
How to calculate it
Count the number of ad requests that returned a served impression and divide by the total number of ad requests fired in the same period. Multiply by 100 to express as a percentage. Unfilled requests — where no bid met the floor price or no demand was available — reduce the fill rate.
Why it matters
Fill rate directly determines how much of a publisher's potential ad inventory is monetised. A low fill rate means impressions are being wasted; a high fill rate at a low floor price may sacrifice yield. Optimising fill rate in combination with eCPM is the core task of ad mediation and floor price management.
Benchmarks & pitfalls
According to AdReact 2026 and Appodeal data, fill rates vary significantly by geography: Tier-1 traffic (primarily US, UK, AU, CA) achieves 85–95%; mixed global inventory 70–85%; and emerging-market inventory 50–70%. These are vendor-reported benchmarks and may reflect publishers already using optimised mediation stacks. Fill rate is also sensitive to floor price settings — raising floors can lower fill rate while improving eCPM, so the two metrics must be read together.