What's the Maximum File Size for a YouTube Ad Video Upload?

Google Ads accepts YouTube ad video uploads up to 256 GB per file, per Google's official video ad specs documentation. That ceiling applies the same way across ad formats, including skippable in-stream, non-skippable in-stream, bumper, and in-feed ads — length limits vary by format, but the file-size cap itself doesn't.

File Size and Length Are Two Separate Limits

It's easy to conflate these, but they're independent constraints. Duration limits, such as the 6-second length typically used for bumper ads or the 15-to-30-second range common for skippable in-stream ads, govern how long the ad plays. The 256 GB figure governs how large the uploaded file can be regardless of length, so a short, high-bitrate or uncompressed video could theoretically be large while a much longer, well-compressed video stays small.

Accepted File Formats

Google's video ad specs list a broad range of accepted video container and codec formats, including MPEG, WMV, AVI, MOV, FLV, MP4, WebM, and ProRes. Audio-only file formats such as MP3, WAV, or PCM are explicitly not accepted, since the upload needs to be a video file, not just a soundtrack.

A Different, Smaller Limit for API Uploads

Advertisers uploading programmatically through the Google Ads API, rather than through the standard Google Ads or YouTube interface, run into a separate and much smaller ceiling: the API's direct upload endpoint caps files at 5,368,709,120 bytes, or roughly 5 GB. Teams building automated upload pipelines need to plan around that 5 GB figure, not the 256 GB interface limit.

Why the File-Size Limit Almost Never Matters

A typical 15-to-30-second ad, encoded at a reasonable bitrate for web delivery, generally lands in the range of a few hundred megabytes at most. Hitting even the much smaller 5 GB API ceiling usually signals an unnecessarily high-bitrate or uncompressed export rather than a legitimate length or quality requirement.

Bottom Line

Export video ads at a standard, properly compressed bitrate and neither the 256 GB interface limit nor the 5 GB API limit will ever come into play — YouTube's real creative constraints are format and length, not file size.

Source: Google Ads Help, "About video ad specs" (support.google.com/google-ads/answer/13547298).