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OmniTools

Image Format Converter

Convert HEIC, AVIF, WebP, JPEG, PNG or GIF to JPEG, PNG or WebP, including iPhone HEIC photos, with a quality control for lossy formats.

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Convert image format

Drop an image, see exactly what was loaded, then convert it. A HEIC from an iPhone works too.

This tool runs entirely in your browser. Nothing you enter is uploaded, stored, or logged.

What this tool does

Format choice is a trade-off between file size and fidelity, and the right answer depends entirely on what the image contains. Converting a photograph to PNG can multiply its size for no benefit, while converting a logo or screenshot to JPEG destroys exactly the sharp edges that made it look good. There is also a format problem nobody asked for: since iOS 11 every iPhone saves photos as HEIC, and no browser can open that format, so an upload form that accepts only JPEG rejects the photo sitting in your camera roll. This converter reads HEIC and AVIF as well as the formats a browser handles natively, and makes the trade-off explicit rather than guessing for you.

How it works

HEIC is the awkward one. It is based on the HEIF standard and stores a photo at roughly half the size of the equivalent JPEG, which is why Apple adopted it, but no browser implements a decoder for it. Safari does not even recognise the image/heic MIME type, so a file that arrived perfectly intact is treated as unreadable. This tool loads a decoder on demand the first time you bring a HEIC in, converts it to pixels, and then works with those pixels like any other image. The file never leaves your device.

AVIF is the modern equivalent for the web and, unlike HEIC, browsers do read it natively, so no extra download is needed to open one. It can be converted out to JPEG, PNG or WebP. It cannot be converted into, because canvas silently returns a PNG when asked to write AVIF, and the only real encoder is a WebAssembly module large enough to be worth avoiding. The tool does not offer an AVIF output rather than hand you a PNG wearing the wrong filename.

PNG is lossless with transparency support, so it stores every pixel exactly. That is correct for screenshots, logos, diagrams, and anything with text or hard edges, and wasteful for photographs. JPEG uses lossy compression tuned for continuous-tone imagery such as photos, achieving far smaller files but discarding detail, and it has no transparency channel. WebP supports transparency, supports both lossy and lossless encoding, and generally beats JPEG at comparable quality.

When converting a photograph from PNG to JPEG, the alpha channel has nowhere to go. The transparent areas must be composited onto a background colour first, and choosing white is usually right for a document but often wrong for a product shot. The tool exposes the background colour so this is an explicit choice. Quality settings also behave very differently across formats: PNG has no quality dial at all, while for JPEG and WebP the file size falls steeply as quality drops, steepest in the middle of the range.

Worked example

A 2.4MB PNG screenshot needs to go under a 200KB upload limit, and an HEIC photo from a phone needs to become a JPEG for a form that only accepts one.

  1. The HEIC is decoded to pixels on the device, giving a normal image to work with
  2. Choose JPEG at quality 0.85 for the photo, which flattens any transparency onto a background
  3. For the PNG screenshot, keep it lossless: convert to WebP, which preserves the hard edges around text
  4. If the WebP is still over the limit, drop the quality to 0.75

WebP typically lands a screenshot between 60% and 85% smaller than PNG at visually identical quality, which usually clears the limit without the artefacts JPEG would introduce around text.

Accuracy and limitations

  • Converting a lossy source to a lossless format cannot recover detail that was already discarded. The output is larger but no better.
  • Converting to JPEG removes transparency. The transparent region is filled with the chosen background colour, which becomes permanent.
  • A HEIC burst contains several frames from one shutter press. Only the first is used, because silently merging them into one image would not be what you asked for.
  • AVIF is read but not written. Every browser can open AVIF and none of them can save it, so the output choices are JPEG, PNG and WebP.
  • Very large images can exceed browser canvas limits (commonly around 16384px per side, and lower on mobile Safari).

Frequently asked questions

How do I convert HEIC to JPG?
Drop the HEIC file in and choose JPEG. No browser can open HEIC on its own, so the tool fetches a decoder the first time you use one, then converts it on your device. The first conversion takes a moment; after that it is instant.
Why can't I upload my iPhone photos to a form?
Almost certainly because they are HEIC. Since iOS 11 the iPhone saves photos in HEIC, which is smaller than JPEG but which most portals, printers and older software refuse. Convert to JPEG and the problem goes away.
Are my HEIC photos uploaded anywhere?
No. The decoder runs in your browser, the conversion happens on your device, and nothing is transmitted. That is the same for every format this tool accepts.
Can you convert to AVIF?
Not from the browser, and this tool will not pretend otherwise. Browsers can read AVIF but cannot write it, and the only real encoder is a multi-megabyte WebAssembly module. Offering it and quietly giving you a PNG instead would be worse than not offering it.
Should I use PNG or JPEG for my image?
PNG for anything with text, hard edges, line art, or transparency: screenshots, logos, diagrams. JPEG for continuous-tone photographs. WebP is usually the better choice for both if the recipient will accept it.
Why did converting to PNG make my file much bigger?
PNG is lossless, so it stores every pixel of a photograph in full. If you started from a JPEG, you are re-expanding data that was already compressed, and saving it losslessly makes it larger. PNG is the wrong format for photographs.
What happens to transparency when I convert to JPEG?
JPEG has no alpha channel, so transparency is discarded and the transparent area is filled with the background colour you choose in the tool. Pick white for documents on white and a colour that matches the intended backdrop for product images.
Is WebP safe to use everywhere?
In all current major browsers, yes. Older software, some email clients, and some print workflows still handle JPEG and PNG more reliably, so check your audience before switching a public-facing workflow to WebP.