Creative Size Validator
Compare VAST creative dimensions against the intended player size and flag mismatches that often lead to scaling issues, startup delay, or poor CTV presentation. Built for video QA and creative-ops checks before launch.
Check whether the creative dimensions fit the player you expect to render it.
What you can do here
- Validate a new creative package before trafficking.
- Explain why a video ad is letterboxed or cropped.
- Check whether a high-resolution asset is overkill for the player.
Before you start
- Enter dimensions such as `1280x720` and `1920x1080`.
Player
1280 x 720
Creative
1920 x 1080
Risk status
Looks aligned
Validation output
The player and creative sizes look compatible.
About Creative Size Validator
The Creative Size Validator compares creative and player dimensions to highlight oversized, undersized, or aspect-ratio-mismatched combinations before they ship.
Use it when a player is stretching, letterboxing, or struggling with startup because the creative was prepared for a different environment.
Best uses for Creative Size Validator
- Validate a new creative package before trafficking.
- Explain why a video ad is letterboxed or cropped.
- Check whether a high-resolution asset is overkill for the player.
How to use Creative Size Validator
- Enter the player size.
- Enter the creative size.
- Review mismatch warnings and launch risk.
What to paste in
- Enter dimensions such as `1280x720` and `1920x1080`.
What you should see
- Risk warnings for oversize, undersize, and aspect-ratio mismatch.
Example checks
These are simple checks you can run when you want a real sample and a clear result to compare against.
Enter dimensions such as `1280x720` and `1920x1080`.
Why run it: Validate a new creative package before trafficking.
What to look for: Risk warnings for oversize, undersize, and aspect-ratio mismatch.
Creative Size Alignment Across Browser Video and CTV
Why dimensions still cause modern video problems
It is easy to assume that modern players will gracefully handle any mismatch between creative dimensions and player size. In reality, size misalignment still causes poor presentation, slower startup, unexpected scaling, and inconsistent device behavior. This is particularly visible in large-screen environments where stretching, cropping, or letterboxing is impossible to ignore.
Creative dimensions are not just about appearance. Oversized assets can increase startup overhead, especially when paired with heavyweight encoding or distant delivery infrastructure. Undersized assets can look visibly soft once scaled to the player. Aspect-ratio mismatches can introduce padding or cropping that undermines creative intent. All of these are operational issues, not just design concerns, because they affect playback quality and campaign acceptance.
That is why size validation belongs in ad QA. Teams already check tags, wrappers, and tracking. Dimension compatibility deserves the same treatment. It is one of the simpler variables to inspect and one of the easiest to fix before launch.
How to interpret size mismatch signals
A good validator should help teams distinguish between acceptable variation and meaningful risk. A creative that is moderately larger than the player may be fine if the aspect ratio matches and delivery is efficient. A creative that is both much larger and differently proportioned is far more suspicious. Likewise, a smaller asset may still be acceptable for a small mobile player but look unacceptable when stretched to a large CTV canvas.
The value of a size check is that it makes those trade-offs explicit. Instead of debating whether a creative 'looks wrong,' the team can see the dimension comparison and document the mismatch. That helps creative operations, trafficking teams, and engineers discuss the issue in shared terms. It also reduces the chance that a presentation complaint is dismissed when the mismatch is clearly measurable.
Dimension checks are most useful when combined with broader media validation. Size alone does not guarantee compatibility. Codec, bitrate, and delivery method still matter. But as a first-pass screen, dimension alignment catches a surprising number of avoidable problems.
Why size validation supports better launch discipline
The broader operational benefit of a size validator is consistency. Without a lightweight tool, teams often rely on memory or informal judgment when deciding whether a creative seems appropriate for a placement. That works until it doesn't. A shared validator standardizes the conversation and provides simple evidence that can be attached to QA notes or launch approvals.
This is especially valuable in organizations where creative packaging and placement ownership are split across teams. The validator gives both sides a common reference point. If a launch risk exists, it can be identified before the asset is trafficked widely or approved for CTV playback. That is much cheaper than discovering the issue after the ad has already reached users.
In short, size validation is small effort with disproportionate payoff. It does not solve every media problem, but it removes one of the simplest and most common classes of avoidable mismatch from the launch process.
Troubleshooting
What to look for
- Risk warnings for oversize, undersize, and aspect-ratio mismatch.
Common issues
- Dimension checks do not account for codec or bitrate compatibility.
Best practices
- Paste raw input so the tool can apply formatting consistently.
- If output looks wrong, validate the input for missing commas or tags.
- Use the example buttons above to sanity-check formatting and behavior.
Related tools
More tools in the vast tools category.
- VAST Inspector - Test and debug VAST tags with full XML inspection, playback simulation, and real-time event tracking—all in one tool. Built for QA teams and video operations specialists, this tool uses the Google IMA SDK to simulate real-world playback and surface issues in tag structure or delivery. Paste your VAST tag to view formatted XML, preview creative playback, and monitor SDK events like load, start, and complete in real time. It’s ideal for troubleshooting wrappers, verifying third-party tags, or confirming tracking pixels. Everything runs client-side for speed and privacy during development and testing.
- VAST Wrapper Visualizer - Paste a VAST tag and map the wrapper chain visually from publisher request to final inline creative. This debugger is built for video QA, ad ops, and CTV teams that need to see wrapper ownership, hop order, and depth risk quickly before escalating an issue to an ad server or SSP.
- VAST Wrapper Latency Analyzer - Measure latency for each VAST wrapper request and flag the hops most likely to push a browser or CTV player beyond its timeout budget. This tool is built for ad ops teams debugging slow supply paths and late inline responses.
- Redirect Chain Analyzer - Trace redirect chains for VAST tags, click trackers, and ad-request URLs with hop-by-hop status codes and latency. Use it when you need to know exactly where an ad-tech URL ends up before it reaches the player or landing page.
Related reading
More specific pages for the exact jobs this tool supports.
VAST Error 203: Video player expecting different size
Returned creative size does not align with what the player expects.
VAST Error 501: NonLinear creative dimensions too large
Non-linear creative dimensions do not align with the available display area.
VAST Error 601: Companion creative dimensions do not fit
Companion dimensions do not fit the available companion slot.
Match Creative Size to Player Requirements
Use the Creative Size Validator when scaling or aspect-ratio issues are likely to matter.
Check a 1080p Creative in a 720p Player
A narrow size-validation workflow for common 1080p vs 720p mismatches.
Validate Vertical Video in a CTV Slot
A long-tail CTV creative-fit page for vertical assets.
Review Companion and Player Size Mismatches Before Launch
A niche launch-QA page for companion and player size checks.
Check Outstream Creative Size Before a Mobile Rollout
A mobile rollout workflow for outstream creative fit.
Frequently asked questions
Is it free to use?
Yes. Core tools are free and accessible without signup.
Does it upload my data?
This tool runs locally in your browser. Data you paste or files you upload stay on your device and are not uploaded.
What if I spot a bug?
Please reach out via the Contact page with a reproduction example.
Does it inspect VAST XML automatically?
The first version compares dimensions you enter manually.
Can it replace creative QA on the target device?
No. It is a quick dimensional check, not a full playback certification step.
Why does aspect ratio matter so much for CTV?
Large-screen playback makes cropping, padding, and upscaling issues much more obvious.