HEIC to PNG converter — lossless output from iPhone HEIC photos

PNG is rarely the right final format for a camera photograph — the file can be several times larger than a JPG — but it is often the right intermediate. If a HEIC photograph will be cropped, annotated, combined into a document or passed through another editor, PNG avoids stacking one lossy encode on top of another.

Support staff and form helpdesks ask for PNG because it opens consistently and preserves hard edges. A converted PNG is also useful when a portal accepts PNG but not HEIC, provided its size limit is generous enough.

As with every tool here, the privacy model is architectural rather than promissory: there is no upload endpoint. The HEIC decoder and PNG encoder run in the tab, and the output is assembled in memory on the device.

Format rejection is the least informative failure a portal can hand you: the upload simply does not appear, or returns a generic error, because the file header says WebP or HEIC while the requirement says JPEG. Converting is a thirty-second fix that removes a whole class of dead ends.

The reverse case matters for the web. Serving WebP or AVIF instead of JPEG typically saves a quarter to half the bytes for the same visual quality, which is free page-speed improvement for anyone with a website or blog.

Conversion is one of the few operations where doing it in the browser is not merely a privacy nicety — passing a photograph through an unknown converter often adds a watermark or silently shrinks it, and neither happens here.

This tool exists for images handled in a hurry: no queue, no account, no upload, and a result you can verify on the spot. The explanation below is the same one we would give a colleague who asked how it works.

Pixels, DPI metadata and physical print size are distinct. For example, 35 mm at 300 pixels per inch is approximately 413 pixels, but pixels alone cannot guarantee a printer produces a 35 mm image. If the instructions also require DPI metadata or a measured print, check those separately.

Photographs from phones carry more metadata than most people realise — capture timestamp, camera model, the orientation tag that decides whether the picture displays upright, and often GPS coordinates precise to a few metres. Because every operation on this site writes a fresh file, that metadata does not survive by default. For a photograph of a marksheet or a bank statement, that is a privacy gain; for an archival photograph, note the date before you process it.

Accepted inputs are JPEG, PNG, WebP, AVIF, HEIC, GIF and BMP images up to 50 MB each. SVG, HTML and other script-bearing formats are refused outright rather than sanitised, because a file that can execute code has no business being re-encoded — and an upload field that accepts one is a security hole rather than a feature. Output is written as PNG, matching the format the destination expects. Several files can be queued where the workbench supports it. Batch, page and memory limits apply; check every output.

HEIC detection uses the file’s ftyp brand, which correctly separates HEIC from AVIF files that share the same container family. libheif decodes the primary image to RGBA pixels; Safari’s native decoder is used when available. OxiPNG then writes a lossless PNG and optimises its compression filters. PNG preserves pixel values from the decoded image, but it cannot recover detail that was never present in the HEIC source. Each format has its own decoder and encoder path. JPEG, PNG, WebP and AVIF are handled by WebAssembly codecs compiled from the reference libraries, so the same quality decisions apply as in a desktop tool. Transparency is preserved for PNG and WebP, and composited onto white for JPEG, which has no alpha channel — the opposite behaviour to naïve converters that leave transparent regions black. Repeated conversion between lossy formats is discouraged in the interface, because each pass costs a little quality. HEIC support is loaded on demand because the decoder is large and most visitors never need it. Detection uses the ISO-BMFF brand in the file header rather than trusting a filename, and output is freshly encoded so stale metadata does not silently travel into the converted photograph.