A 25 MB WEBP test file

About this file

A 25 MB test file in WEBP format, sized to exactly 26,214,400 bytes. Free to download with no signup, for verifying upload limits and file-handling behaviour.

The MD5, SHA-1 and SHA-256 values listed above are the real digests of this file. Recomputing them after download confirms the transfer was not corrupted, and they double as known-good expected values when testing a hashing library.

What this size means in practice

25 MB is widely known as the Gmail attachment limit. In practice, though, mail attachments are Base64-encoded and grow about 33%, so a 25 MB file becomes roughly 33 MB on the wire and usually will not send as-is.

That gap between the advertised limit and the post-encoding size is a pitfall every mail-sending feature eventually hits. Use this file to check whether your size validation runs before or after encoding.

Getting a feel for this size

On a 10 Mbps link the transfer takes roughly 21 seconds, and about 2.1 seconds at 100 Mbps. Base64-encoded it grows to roughly 34,133 KB.

Estimating a photographic WEBP at roughly 0.15 bytes per pixel, this size works out to around 174,762,667 pixels — about 15,265 × 11,449 px at a 4:3 aspect ratio. Compression varies enormously with image content, so treat this purely as an order-of-magnitude figure.

What to check for this format

WebP uses a RIFF container: the file starts with RIFF and has WEBP at byte 9. It supports lossy, lossless, alpha, and animation — but detecting it from the extension or only the first four bytes risks confusing it with other RIFF-based formats.

• Whether your server-side image library actually supports WebP — older GD or ImageMagick builds may not
• Whether it is served as image/webp — a wrong Content-Type makes browsers download instead of render it
• Whether the JPEG / PNG fallback in your <picture> element works for unsupported clients