What Are Pre-Roll Ads?

Pre-roll ads are short video advertisements that play automatically before the viewer’s selected video content begins. They typically last between 6 and 30 seconds and appear across YouTube, Twitch, Facebook, OTT apps, and custom video players.

For content creators, broadcasters, and streaming platform operators, understanding pre-roll ads is critical for generating revenue from live streams and on-demand video. Yet many streamers still don’t know how these ads work or how to set them up.

This guide will explain what pre-roll ads are, how they work, the different types available, their benefits and drawbacks, and how streaming platforms use them to generate ad revenue.

What Is A Pre-Roll Ad?

A pre-roll ad is a short promotional video advertisement that plays automatically before the viewer’s selected video content begins. These video ads are typically six to 30 seconds long. They can appear across social media platforms, video-on-demand environments, streaming services, and websites with embedded video players.

Pre-roll ads are a subtype of in-stream video ads. In-stream ads are advertisements that play within a video stream rather than alongside it. The term “pre-roll” refers to the specific placement — before the main content starts. The ad appears automatically when a viewer clicks play. This guarantees the advertising message is delivered before the featured video begins.

You’ll find pre-roll ads on platforms like YouTube, Facebook, Twitch, X (formerly Twitter), and connected TV apps. Broadcasters who host video on their own websites can also run pre-roll ads through custom HTML5 video players that support ad tags. Streaming platforms like Castr supports enabling skippable pre-roll ads as a way to make it a more comfortable viewing experience for your audience.

Types of Pre-Roll Ads

Pre-roll ads come in three main formats. Each type differs in length, viewer interaction, and billing model. The right choice depends on your campaign goals and audience tolerance.

Skippable Pre-Roll Ads

Skippable pre-roll ads give viewers the option to skip the ad after five seconds. Advertisers only pay when the viewer watches 30 seconds, the full ad, or interacts with it — whichever comes first. This is the model behind YouTube’s TrueView format.

Skippable ads reduce viewer frustration. But they demand a strong opening hook. If your first five seconds don’t grab attention, most viewers will hit the skip button immediately.

Non-Skippable Pre-Roll Ads

Non-skippable pre-roll ads require viewers to watch the entire advertisement before accessing their content. These ads typically run 15 to 20 seconds. YouTube also offers a 30-second non-skippable format on its connected TV app.

Non-skippable ads achieve higher completion rates — as high as 80%, compared to roughly 40% for skippable formats. However, they can cause viewer frustration if the creative is too long or poorly targeted. National advertisers and brands running awareness campaigns commonly use this format.

Bumper Ads

Bumper ads are short, non-skippable pre-roll ads lasting only six seconds. They use CPM (cost-per-thousand-impressions) bidding rather than pay-per-view. Google found that 9 out of 10 bumper ad campaigns drove a significant lift in ad recall.

Bumper ads work well for mobile users because they’re quick and easy to watch. They’re ideal for high-frequency branding campaigns where the goal is broad reach and message repetition rather than detailed storytelling.

Quick Comparison:

How Do Pre-Roll Ads Work?

The viewer experience is simple: you click play, a short ad runs, and then your video starts. Behind the scenes, the process involves several technical steps.

Pre-roll ads work by automatically playing before the main video content loads. The viewer must watch at least a portion of the advertisement before accessing their desired content.

Targeting

Pre-roll ads allow precise targeting based on demographics, interests, viewing patterns, and even the topic of the featured video. This targeting is powered by viewer data collected by the ad platform or ad server.

Ad Delivery Methods

From a technical standpoint, pre-roll ad delivery happens through one of two methods.

Client-side ad insertion (CSAI) loads the ad separately in the video player on the viewer’s device. The player requests an ad from an ad server, plays it, and then loads the main content.

Server-side ad insertion (SSAI) takes a different approach — it stitches the ad directly into the video stream on the server before the stream reaches the viewer’s device. SSAI creates a seamless, buffer-free experience and is harder for ad blockers to detect.

Industry Standards

Both methods rely on industry standards called VAST (Video Ad Serving Template) and VPAID (Video Player Ad Interface Definition). These protocols allow ads to be served consistently across different video players, websites, and apps.

Benefits of Pre-Roll Ads

Pre-roll ads offer clear advantages for both advertisers and publishers. Here are the key benefits:

• Guaranteed exposure. Pre-roll ads are hard to ignore because viewing them is a prerequisite for accessing the main content. Every viewer sees at least the first few seconds of the ad.
• Strong brand recall. The upfront placement reaches audiences during moments of peak anticipation. A Nielsen study commissioned by Facebook found that viewers who watched even one second of a pre-roll ad showed an increase in brand awareness and purchase intent.
• Precise audience targeting. Pre-roll ads use viewer data for demographic, interest, and behavioral targeting. Advertisers can reach specific audience segments based on age, location, interests, and viewing habits.
• Measurable performance. Pre-roll ads provide clear metrics including completion rates, view-through rates, click-through rates, and engagement data. These insights help advertisers optimize campaigns over time.
• Less intrusive than other formats. A 2017 study by IPG Media Lab and YuMe found that pre-roll ads are 3.5 times less likely to be considered “interruptive” than outstream and mid-roll ad formats on both desktop and mobile. Users also rated pre-roll ads as more informative and engaging than other video ad types.
• Revenue generation for publishers. For content creators and streaming platforms using ad-supported video (AVOD) models, pre-roll ads are a primary revenue stream. They monetize every video view without requiring viewers to pay a subscription fee.

Drawbacks of Pre-Roll Ads

No ad format is perfect. Pre-roll ads have several limitations that advertisers and publishers should understand:

• High skip rates. A 2024 IAB report revealed that digital video ad spend in the U.S. climbed 15% year-over-year. An older study also found that 65% of viewers skip the moment the button becomes available — mostly out of habit.
• Viewer frustration. Unexpected or irrelevant ad appearances can irritate users. If the ad doesn’t match the viewer’s interests or the content they selected, the negative perception can extend to the advertised brand.
• Limited time to convey a message. With only 5 to 6 unskippable seconds before the skip button appears, advertisers must capture attention almost instantly. Complex messages or detailed product explanations don’t fit this format well.
• Ad blocker vulnerability. Client-side pre-roll ads can be blocked by ad-blocking software, reducing impressions and revenue. Server-side ad insertion (SSAI) mitigates this problem by stitching ads directly into the video stream, making them undetectable by most ad blockers.

These drawbacks can be addressed through strong creative, proper audience targeting, shorter ad lengths, and SSAI technology that bypasses ad blockers and eliminates buffering.

Pre-Roll Ads vs. Mid-Roll vs. Post-Roll Ads

The primary difference between pre-roll, mid-roll, and post-roll advertising is when the ads appear during the content viewing experience. Each placement offers unique advantages and challenges based on viewer attention, engagement levels, and content context.

Pre-roll ads capture early impressions and work best for brand awareness. Mid-roll ads drive higher CPMs because viewers are already engaged with the content, but poorly timed mid-rolls can cause viewers to leave. Post-roll ads are the least intrusive but often ignored because the content has already ended.

For publishers choosing between these formats, the decision depends on content length, audience behavior, and AVOD, SVOD, and TVOD monetization models. Short-form content typically works best with pre-roll only. Long-form content can support all three placements.

Where Do Pre-Roll Ads Appear?

Pre-roll ads are common across a wide range of platforms and video environments:

• YouTube — Skippable TrueView ads and non-skippable ads play before selected videos. Pre-roll ads are automatically turned on for monetized live streams.
• Facebook — Pre-roll ads are limited to six seconds and appear in search results, Page timelines, and the Watch section.
• Twitch — Pre-roll ads typically run 15 to 30 seconds and are non-skippable. Streamers can reduce pre-roll frequency by running mid-roll ads during their streams.
• X (formerly Twitter) — Amplify pre-roll ads play before premium publisher video content. Viewers can skip after six seconds.
• OTT and CTV platforms — Streaming services like Hulu, Prime Video, Roku, Apple TV, and Fire TV show pre-roll ads before on-demand shows, movies, and live streams.
• Custom video players on websites — Broadcasters and media companies who host video on their own websites can run pre-roll ads through an embeddable HTML5 video player that supports VAST/VPAID ad tags. This gives publishers full control over their ad inventory and revenue.

Pre-Roll Ads in Live Streaming: How Broadcasters Monetize Content

Pre-roll ads run before the live stream begins. On YouTube, pre-roll ads are automatically turned on for live streams when monetization is enabled. These ads are viewable on both mobile and desktop. Pre-roll video ads offer an effective way to monetize live streams because they provide a brief pause before the broadcast starts — a less intrusive alternative to mid-roll ads that interrupt the stream.

This matters for a wide range of broadcasters. Churches streaming weekly worship services can generate ad revenue to offset platform costs. Sports broadcasters running geo-blocked live events can pair pre-roll ads with regional targeting. Corporate event producers can use pre-roll ads on internal town halls delivered through private streaming platforms. Media companies operating 24/7 linear channels on OTT apps can run pre-roll ads before every viewer session.

Pre-roll ads fit within the AVOD (ad-supported video on demand) monetization model. AVOD lets viewers watch content for free while the publisher earns revenue from ads. This is one of three common video monetization approaches — alongside SVOD (subscription-based) and TVOD (transactional/pay-per-view). Many live streaming platforms support all three models, giving publishers flexibility to mix ad revenue with subscription and pay-per-view income through tools like paywall and ad monetization.

How Server-Side Ad Insertion (SSAI) Powers Pre-Roll Ads

SSAI is technology that stitches together ads within a video stream before the stream loads on a user’s device. Instead of the video player loading the ad separately (as in client-side insertion), the server combines the ad and the content into a single stream. The viewer receives one continuous video with no buffering or loading delays between the ad and the main content.

This matters for two reasons. First, CSAI — which inserts ads on the client side — is more susceptible to ad blocking. SSAI is less affected by ad blockers because it stitches in the ads at the point of encoding. The ad looks like part of the video stream, so ad-blocking software can’t distinguish it from the content. Second, SSAI provides a seamless viewing experience that’s critical for live streaming, where any buffering or delay between the ad and the stream can cause viewers to leave.

Castr supports SSAI with VAST/VPAID integration, allowing broadcasters to insert pre-roll ads into live streams and VOD content without buffering or ad-blocker interference. This is especially valuable for sports broadcasters, media companies, and OTT platform operators who need reliable ad delivery across all devices.

Best Practices for Creating Effective Pre-Roll Ads

Whether you’re an advertiser creating pre-roll ads or a publisher advising your ad partners, these six practices will improve performance:

1. Hook viewers in the first three seconds. Effective pre-roll ads capture attention immediately. Use a bold visual, a surprising statement, or a direct question. Viewer interest must be earned before the skip button appears at the five-second mark.
2. Show your brand early. Facebook research found that clips featuring the brand in the first three seconds have a 1.23x higher recall rate than those that don’t. Don’t save your brand name for the end — most viewers won’t make it there.
3. Design for sound-off viewing. Many platforms default to muted playback, especially on mobile. Use captions, bold text overlays, and strong visuals that communicate your message even without audio.
4. Keep it short. Ads under 20 seconds have higher completion rates than longer formats. A 15-second ad hits the sweet spot between message delivery and viewer patience. A 20-second ad has a 4% higher completion rate than a 30-second ad.
5. Optimize for mobile. Most video consumption happens on mobile devices. Use vertical or square formats where the platform supports them. Make sure text is large enough to read on small screens.
6. Include a clear call to action. Tell viewers exactly what to do next — visit a website, sign up for a free trial, or learn more. A pre-roll ad without a CTA is a missed conversion opportunity.

How to Add Pre-Roll Ads to Your Streaming Platform

If you’re a publisher or broadcaster who wants to run pre-roll ads on your own platform, here’s a step-by-step overview:

Step 1: Choose a video player with ad support.
You need an HTML5 video player that supports VAST and VPAID ad tags. Castr provides a customizable HTML5 video player with built-in ad insertion support that can be embedded on any website.

Step 2: Select a monetization platform or ad server.
Connect with an ad server like Google Ad Manager, FreeWheel, or a programmatic ad platform. This is where advertisers bid on your ad inventory and where ad creatives are stored.

Step 3: Configure your ad tags.
Insert your VAST tag URL into your video player settings. The VAST tag tells the player where to find the ad, how long it should run, and what tracking pixels to fire. Set the ad placement to “pre-roll” so the ad plays before the main content.

Step 4: Set targeting and frequency rules.
Define audience targeting parameters like geography, demographics, and interests. Set frequency caps to prevent the same viewer from seeing the same ad too many times. If you serve geo-blocked content, align your ad targeting with your content restrictions.

Step 5: Monitor performance.
Track completion rates, fill rates, CPM, and revenue through your analytics dashboard. Castr provides built-in stream health analytics and revenue reporting to help publishers optimize their ad strategy.

For broadcasters who want to go beyond website embedding, Castr’s white-label OTT app builder lets you launch branded video apps on iOS, Android, Roku, Apple TV, Fire TV, and more — with ad monetization built in. Start your free 7-day trial with Castr to add pre-roll ads to your streams — no credit card required.