Why did a higher floor price increase CPM but reduce total ad revenue?
A higher floor can raise average CPM while reducing total revenue if it removes too many eligible bids. Judge the change with revenue per session or request, fill, bid density and latency, using a matched holdout by placement, market and device instead of CPM alone.
Average CPM only describes the impressions that still cleared. It does not show the auctions lost when a new floor filtered lower bids. A floor change can make the reported CPM look better while fill, competition and total monetized requests fall enough to reduce revenue.
Segment the result by placement, geography, device and demand path. Compare revenue per session or thousand requests, fill rate, bid rate, bid distribution and request volume against a stable holdout. Watch for buyers shifting spend to other supply and for request or page latency changes that alter the comparison.
Roll back or narrow the rule where incremental CPM does not cover the lost fill. Expand only after the holdout shows a durable revenue lift, and keep monitoring bid density so the rule does not silently reduce auction competition over time.
Which metric should I use to evaluate a floor change?
Use total revenue normalized by sessions or ad requests, then inspect CPM, fill and bid density as supporting metrics. CPM alone can hide lost auctions.
Why use a holdout for pricing changes?
A matched holdout separates the effect of the pricing rule from seasonality, traffic mix and demand changes that happened at the same time.
Updated August 4, 2026. Guidance is based on current simulator evidence, recurring support patterns and the official resources linked above.