Fill Rate

Fill rate is the percentage of ad requests that result in a paid impression. The numerator is "filled requests" (a creative was returned and rendered); the denominator is "total requests" (any time the player asked for an ad). 100% fill means every slot was monetized; 50% fill means half the inventory ran a house ad, default content, or blank.

Fill rate is the headline supply-side metric. On the web, mature publishers run 90-95% fill. On CTV, premium inventory runs ~80-90% fill (the gap is driven by frequency caps and creative-availability mismatches). On DOOH, fill is the most variable, established networks (Vistar, Reach TV) run 75-85%; small or new networks can be sub-50% as buyers don't yet have demand routed.

Low fill is almost always a buy-side connectivity problem, not an inventory-quality problem. The fix is more SSP / exchange / DSP connections; not deeper price discounts. A screen with $15 CPM and 50% fill earns less than a screen with $8 CPM and 95% fill.

Trillboards specifically architected its supply layer for high-fill: parallel auction logic across multiple integrated SSPs plus a house ad fallback for slots that don't fill from programmatic. The result is sustained fill at ~90% across the active screen fleet, see partner SDK for the integration approach.