Quick Answer: Why Is CTV Fill Rate Low?
Most CTV ad slots never get sold. A 2025 industry study by Omdia found that ad-supported CTV services fill only about 65% of their commercial ad capacity. That means roughly one in three CTV ad breaks airs with no ad, or a lower-value filler ad, instead of a paid one.
The good news: most of that gap comes from fixable problems, not a lack of buyer demand. This guide covers what actually causes low CTV fill rate, and what publishers do to fix it.
What Fill Rate Actually Means
Fill rate is simple to define it's the percentage of your ad requests that come back with an ad to show, instead of coming back empty.
What's not simple is naming one "good" number for CTV. Fill rate swings a lot by device, time of day, content type, and region. Be careful of anyone who gives you one flat target number without asking about your setup first.
What we do have is a real industry benchmark: Omdia's 2025 research, covering AVOD, FAST, and broadcaster VoD services across eight countries (US, UK, Australia, Brazil, Canada, France, Germany, and Mexico), found the industry filling only 65% of commercial ad capacity on average. That gap is your opportunity. Omdia estimates revenue could grow two to three times if publishers closed it.
Why CTV Fill Rates Drop
Your program data isn't reaching buyers
Peer39, an ad verification company that reviews more than 2.5 billion CTV bid requests every day, found that program information (what show is playing, what it's about) often gets stripped out before it reaches the buyer. This can happen at three points:
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At your end — your team may lack the engineering time to map show details into the bid request, or may intentionally leave them out to protect competitive information.
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At the SSP — supply-side platforms sometimes compress bid requests to save space and speed, dropping content fields in the process.
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At the buyer's end — demand-side platforms may not display or pass along the content fields they do receive.
Buyers who can't see what they're bidding on tend to bid lower, or not at all. This is one of the most fixable causes of lost fill, because it's a data-plumbing problem, not a demand problem.
Sometimes the demand simply isn't there yet
Not every low fill rate is your fault. The IAB Europe Guide to Programmatic CTV found that in several European markets, buyer demand for premium CTV inventory already outpaces the supply available to sell. In markets or verticals like this, the fix isn't a better setup on your end — it's finding more CTV-native demand partners who actually have buyers ready to spend.
The usual operational suspects
Beyond the data and demand issues above, ad ops teams commonly point to a few recurring, fixable causes:
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Demand partners that aren't truly CTV-focused. A partner built for web or app traffic often can't fill CTV slots well, no matter how much inventory you send them.
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Weak audience segmentation. Buyers want to target by device type, content category, and time of day. If your data is too generic, they skip the auction.
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Price floors set without checking real demand. A floor set to protect your average CPM can price you out of the auction entirely if it doesn't match what buyers are actually willing to pay.
How to Raise CPM Without Hurting Fill Rate
The instinct to raise your price floor to boost CPM often backfires. Omdia's research points to a better lever: filling more of what you already have, rather than charging more for less of it. Their model shows total revenue could grow two to three times just by closing the fill gap — without needing higher prices at all.
Practical steps that raise effective CPM without starving fill:
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Set floors by segment (device, daypart, content type) instead of one flat floor across all inventory.
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Test floor changes on a small slice of inventory before rolling them out everywhere.
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Prioritize demand partners who consistently win at your current floor, and renegotiate or replace ones who rarely clear it.
Diagnosing Low Fill Rate Despite Good Viewership
It's confusing when your audience numbers look healthy, but your fill rate doesn't. The most common reason: you're looking at CTV as one bucket, when it behaves very differently by device.
Peer39's Q2 2026 benchmark report, based on more than 322 million CTV ad starts, found TV screens made up 84.85% of all starts analyzed, with mobile phones at just 1.15%. Completion rates also varied sharply by device: around 89% on TV screens, compared with 62.56% on mobile phones.
If your reporting blends every device into one number, a strong TV-screen audience can hide a weak mobile OTT segment dragging your averages down, or vice versa. Break your fill and completion data out by device before assuming your whole CTV strategy needs a rework — you may only need to fix one segment.
Choosing an SSP That Actually Helps Fill Rate
Not every SSP that supports CTV is built for it. Before signing on with one, ask:
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Does it bring real CTV-native demand, or route your inventory through generalist buyers who rarely bid on TV screens?
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Does it pass your program metadata through cleanly, rather than stripping it during compression (the exact problem Peer39 identified above)?
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Can it report fill and completion rate broken out by device, not just as one blended number?
An SSP that can't answer these clearly is likely to reproduce the same fill problems no matter how you configure it.
Managing Multiple Demand Partners
Most publishers need more than one demand source to fill CTV inventory well, but more partners isn't automatically better. A few principles:
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Diversify deliberately. Different partners bring different buyer pools; overlapping partners just compete for the same few buyers.
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Review performance regularly, not just at setup. A partner that filled well last year may have quietly stopped prioritizing CTV.
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Don't let underperformers linger. A partner that rarely wins auctions at your floor is taking up bid-stream slots that a better-matched partner could use instead.
For the deeper technical side of this — GAM line item priorities, bid audits, and timeout configuration — see our Advanced CTV Monetization Tactics guide.
Quick-Wins Checklist
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Check whether your program metadata is actually reaching buyers intact, not just being sent.
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Break your fill rate and completion rate reports out by device.
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Test segment-based floors instead of one flat floor.
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Confirm each demand partner has real, active CTV buyers, not just CTV as a checkbox.
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Review demand partner performance on a set schedule, not just once at onboarding.
Frequently Asked Questions
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What is a good CTV fill rate?
There's no single universal number, since fill rate varies by device, content type, and region. What we do know: Omdia's 2025 research found the ad-supported CTV industry filling only about 65% of commercial capacity on average — meaning most publishers have real room to improve, whatever their starting point.
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Why is my CTV fill rate low even though my viewership is fine?
This is often a device or data problem, not an audience problem. CTV performance varies a lot by device — Peer39 found completion rates of about 89% on TV screens versus 62.56% on mobile phones in the same dataset. Blended reporting can hide a weak segment behind a strong one.
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Does raising ad prices lower fill rate?
Often, yes. Omdia's research suggests publishers get more total revenue by filling more of their existing inventory than by charging more for less of it. Price floors that don't match real demand just leave slots unsold.
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How many SSPs should a CTV publisher use?
Enough to bring genuinely different buyer pools, without spreading your inventory so thin that no single partner has enough volume to optimize well. There's no fixed number — it depends on how much inventory you have and how CTV-focused each partner actually is.
If you'd rather have a team audit your fill rate directly, see our CTV Monetization services.
If you’re not making the most of your ad space, you’re leaving money on the table. MagicBid helps web, app, and CTV publishers maximize revenue with smarter ad placement and optimization tools.
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With MagicBid’s advanced ad tech and expert support, you can turn your traffic into higher earnings without the guesswork. Connect with us now to get a free ad revenue evaluation.
