Calculator

Definition

In digital advertising, Ad Fill Rate is a Key Performance Indicator (KPI) representing the percentage of ad requests that result in the successful delivery of an advertisement. It measures the ability of an ad network or ad server to monetize the available inventory provided by a publisher.

A fill rate of 100% indicates that every ad request resulted in an impression. Conversely, a lower fill rate implies that a portion of the inventory remains unsold or technically unable to display, often referred to as “unfilled impressions” or “passbacks.”

Formula

The standard formula for calculating Ad Fill Rate is:

Where:

• Total Ads Shown (also known as Paid Impressions) is the count of ads successfully rendered on the user’s device.
• Total Ad Requests is the count of calls made to the ad server initiating a bid or fetch for an ad.

Analysis of Results

Benchmarks

While benchmarks vary by industry, geo-location, and ad format, a fill rate above 90% is generally considered efficient for display advertising. Video advertising often sees lower fill rates due to stricter technical requirements (e.g., VAST/VPAID compliance) and higher latency sensitivity.

Causes of Low Fill Rate

Several factors can contribute to a discrepancy between requests and shown ads:

• Technical Latency: The user navigates away from the page before the ad loads.
• Floor Prices: The minimum bid price (floor) set by the publisher is too high for advertisers.
• Inventory Quality: Advertisers may blacklist specific URLs or domains.
• Ad Blockers: Client-side software may block the ad rendering call even if the request was initiated.