THM to WEBP

Trying to open a THM as WEBP? Here's the honest answer — and how to get a real image.

We can't convert THM to WEBP — an THM file can't be opened by any converter. Here's why, and what actually works.

What you can do instead

Why THM to WEBP isn't possible

1

THM can't be decoded

THM is a proprietary/undocumented format that no image library or converter can decode, so it can't be read as a source file.

2

There's no picture to convert

Because nothing can read the THM container, there's no image data a converter can extract and re-save as WEBP. Any tool that claims to do it would just fail.

3

Get the original photos instead

The real photos an THM cache was built from live in your photo library or a backup. Export those (they'll be JPG or HEIC), then convert them — that's a conversion that works.

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Format details

THM is a small JPEG thumbnail saved alongside camera photos and videos — really a JPEG with a different extension.

Full nameThumbnail Image
Developed byCamera makers
Released
Extension.thm
MIME typeimage/jpeg
TransparencyNo

Rename or convert THM to .jpg to open it anywhere.

WEBP is a modern Google format using lossy and lossless compression to make images ~25–35% smaller than JPG or PNG at similar quality, with transparency and animation support.

Full nameWeb Picture format
Developed byGoogle
Released2010
Extension.webp
MIME typeimage/webp
TransparencyYes

WEBP opens in all modern browsers and recent Photoshop, GIMP and image viewers.

Frequently asked questions

No. THM is a proprietary thumbnail-cache blob that no image library can decode, so there's nothing to convert. Export the original photos and convert those instead.

THM files aren't meant to be opened directly. Recover the original images from your device's photo library or an iTunes/Finder backup, then work with those.

Once you have the real photos (JPG or HEIC), they convert cleanly to PNG, JPG or TIFF — free, no sign-up, no watermark.