Why your HEIC file won't convert, and how to fix it

Browser-based converters decode HEIC with a WebAssembly build of libheif and, where available, the browser's own decoder. That covers the vast majority of iPhone photos — but not all of them. When a file fails here (or on any in-browser tool), it is almost always one of these five causes.

1. The file isn't really a HEIC

Surprisingly common: a JPG or PNG that was at some point renamed to .heic, or a download that was cut off halfway. A truncated or mislabeled file fails immediately. Fix: re-download or re-export the original; if it came via chat, ask for it to be sent "as a file/document" rather than as a compressed preview.

2. 10-bit HDR or Dolby Vision variants

Newer iPhones can capture HDR photos with 10-bit color depth. Some of these variants are outside what current browser decoders handle. Fix: open the photo in the iPhone Photos app, make any trivial edit (rotate and rotate back) and save — iOS re-encodes it in a standard profile — or share it via Mail, which produces a JPG directly.

3. Burst, Live Photo or multi-image containers

A HEIC container can hold multiple images: bursts, exposure stacks, the still of a Live Photo plus auxiliary data. Decoders that expect a single primary image can stumble on unusual constructions. Fix: in the Photos app, pick the specific frame you want (for bursts: select the key photo) and export that single image.

4. The photo is too large for browser memory

Decoding happens in RAM, and a 48-megapixel ProRAW-adjacent HEIC can need hundreds of megabytes once unpacked. Mobile browsers in particular may abort. Fix: try on a desktop browser, close other tabs, or export a resized version from your phone first. This site also caps input at 25 MB per file for exactly this reason.

5. The decoder library didn't load

The WebAssembly decoder is fetched from a CDN when the page loads. Ad blockers, strict corporate firewalls or flaky connections can block it. The site then falls back to the browser's native decoder, which on Windows depends on installed codecs. Fix: reload the page, temporarily allow the cdn.jsdelivr.net domain, or try another network/browser.

Still stuck?

The two universal escape hatches: (1) e-mail the photo to yourself from the iPhone — iOS converts it to JPG in transit; (2) on Windows/macOS, open the file in any app that decodes HEIC (Photos with codecs, GIMP, IrfanView) and export as JPG. And if a particular file consistently fails here while opening fine elsewhere, we genuinely want to know — see the contact page.