Why an iPhone Photo Can Fail on Windows
HEIC is Apple's High Efficiency Image Container. It keeps camera photos compact while preserving detail, but compatibility depends on the device and application receiving the file. A job portal, family PC, legacy editor, or Android app may reject it even when the photo looks normal on the iPhone.
Converting to JPG makes the image readable almost everywhere. The trade-off is that JPG uses lossy compression and does not keep transparency, Live Photo motion, or every HEIC-specific metadata feature.
Use JPG for Photos and PNG for Screenshots
For a camera photo headed to email, a form, or a general-purpose website, export JPG at a quality around 85–90%. That normally preserves visual detail while producing a familiar file type.
For an iPhone screenshot containing small text, UI edges, or a transparent sticker, use PNG instead. PNG is larger but avoids the halos and block artifacts that JPG can add around high-contrast text.
If a portal has a file-size cap, convert first, then use a target-size compressor. Reducing dimensions slightly usually looks better than forcing JPG quality extremely low.
A Safer Local Workflow
Choose the HEIC file, select JPG, check the preview, and download the converted copy. Keep the original HEIC until you confirm the receiving service accepts the JPG.
For personal photos, IDs, or work material, prefer a workflow that performs decoding and encoding in the browser. The useful privacy question is not whether the page makes any network request while loading; it is whether your selected image file is uploaded for processing.