Runway input limits: 16 MB image, 32 MB video, HEAD required

Runway rejects a media URL that is not HTTPS, uses an IP address instead of a hostname, lacks a valid Content-Type and Content-Length, redirects, is over 2048 characters or cannot answer a HEAD request. Size limits for URLs are 16 MB for images and 32 MB for video and audio. Sume asks for public HTTPS input URLs, so the same checklist is a safe way to host files for both.

Runway's URL rules

These are Runway's own rules, quoted in short. A generic application/octet-stream type is explicitly not supported, file extensions in the URL are ignored, and Runway's fetcher identifies itself with a User-Agent that starts with RunwayML API/, so a WAF needs to allow it.

What Sume documents

Sume's pages say the input URLs must be public and HTTPS, and that an unreachable input is a failure, with codes such as input_media_unreachable and image_not_fetchable in the error table. They do not publish Runway-style details about HEAD, redirects or length, so do not rely on a lenient fetcher. Host the file the strict way.

A pre-flight check

A short pre-flight check saves a failed job:

• Request the URL with HEAD and confirm a 200 with the right Content-Type.
• Follow no redirects: link straight to the final object.
• Keep the URL under 2048 characters.
• Fetch it from outside your network, since private hosts fail.

Passing is not accepting

Passing this check does not guarantee a model will accept the media. Each model has its own limits on length, size and format, so keep reading the catalog for the model you pin.