Fill Rate

What is a Fill Rate?

Fill rate is a core metric in digital advertising – particularly for FAST (free ad-supported streaming TV) and AVOD (Advertising-based Video On Demand) platforms. It measures the percentage of ad requests that result in a successfully served advertisement. A high fill rate means more of your available ad inventory is being monetized, directly boosting revenue. A low fill rate, on the other hand, points to inefficiencies that could lead to missed revenue opportunities.

In the streaming ecosystem, fill rate is critical. It reflects how effectively your ad tech stack is matching demand with supply and is a key indicator of how well you’re monetizing your content.

How is the ad fill rate calculated?

The fill rate formula is straightforward:

Fill Rate (%) = (Total Ads Served ÷ Total Ad Requests) × 100

For example, if your platform sends out 1,000,000 ad requests and receives 900,000 valid ad impressions in return, your fill rate would be 90%.

Why does fill rate matter for FAST and AVOD channels?

For streamers and content publishers, fill rate directly impacts monetization. When ad slots go unfilled, you’re not just losing ad revenue — you’re creating empty ad breaks that can degrade viewer experience and hurt brand relationships.

High fill rates improve both monetization and user experience:

• More revenue: Every filled slot contributes to your bottom line.
• Better viewer retention: Properly filled ad breaks feel more premium and consistent.
• Advertiser trust: Consistent fill builds confidence in campaign delivery and performance.

What factors affect fill rate?

Several factors can influence whether an ad request results in a served ad:

• Demand availability: The number and diversity of advertisers bidding on your inventory.
• Audience targeting: Misaligned targeting criteria can lead to fewer matches and unfilled slots.
• Technical issues: Errors in ad requests, long load times, or incorrect tagging can prevent ad delivery.
• Scheduling inefficiencies: Ad break lengths or timing that don’t align with available creatives can leave time unfilled.

How can you increase ad fill rates?

Here are the top strategies to help FAST and AVOD platforms boost their fill rates and increase revenue:

1. Expand the demand pool

Partnering with the largest DSPs (demand-side platforms), direct programmatic buyers, and brand advertisers ensures a solid demand base for your channel. It’s also key to diversify your demand sources to minimize the amount of unsold ad space without devaluing the inventory.

2. Optimize ad break scheduling

Scheduling is a major driver of fill rate. Some best practices include:

• Stick to standardized ad lengths: Most ads are 15 or 30 seconds long. Schedule ad pods that are divisible by 30 to avoid unfillable gaps.
• Prioritize longer viewing sessions: Viewers in longer sessions are less likely to churn during ad breaks, leading to more completed ad views and fewer missed impressions.
• Use promos to fill time: If an ad pod is under-filled, short house promos can maintain the viewer experience while preserving monetization potential.

3. Eliminate technical errors

Technical breakdowns in the ad delivery chain are a silent killer of fill rates. To address this:

• Test VAST tags and ad responses: Ensure all integrations are error-free.
• Avoid reusing Ad IDs: Ad servers may interpret reused IDs as new creatives, which can cause unnecessary transcoding or ad rejection.
• Monitor server logs and reporting: Look for patterns of unfilled requests to troubleshoot delivery issues quickly.

How does Wurl help maximize fill?

Wurl’s AdPool connects your inventory to a broad network of premium demand sources — including DSPs, direct advertisers, and exclusive AppLovin performance marketers. By aggregating demand in one place, AdPool helps drive higher fill rates and better eCPMs across your ad inventory.

With net-15 payment terms, you’ll also benefit from faster cash flow — a major advantage for scaling operations and reinvesting in content or tech.

Get started increasing your fill rate with AdPool.