Two modern formats with different homes
HEIC and WebP were both created to replace JPG, and both succeed at it technically. HEIC, Apple's default camera format since 2017, wraps HEVC video compression around still images and adds 10-bit colour, the P3 gamut and room for Live Photo clips. WebP, Google's format from 2010, wraps VP8 compression around still images and is decoded by every browser in use. The difference is where they live. HEIC is at home in Apple's Photos app and almost nowhere else. WebP is at home on the web and in most modern software. Converting between them is what you do when a phone photo needs to go on a website without paying the JPG size penalty.
How the conversion runs
Browsers cannot decode HEIC, so this page loads heic2any, a JavaScript port of libheif, on first use. It is a few megabytes, so the first conversion of a session waits for the download; later ones do not. The decoder produces a lossless PNG in memory, which is handed to a Web Worker that decodes it again and encodes WebP with the WebAssembly build of libwebp. The extra decode pass is why this converter feels slower than, say, JPG to WebP: two to six seconds per 12 megapixel photo on a laptop is normal, and phones take longer. The file never leaves your device.
What survives and what does not
The primary image survives. Live Photo video, burst frames and depth maps do not. Colour is reduced from 10-bit P3 to 8-bit sRGB, and HDR gain maps are dropped, so bright skies may look a touch less luminous than on the phone screen. Metadata is fully stripped, including GPS coordinates and capture time, because the pixels travel through a canvas. That is a good default for publishing, and if you want to see what was in the file first, the EXIF viewer reads it without converting anything. WebP does support transparency, but iPhone photos have none, so this rarely matters here.
Quality settings and a worked example
The slider spans 20 to 95 with a default of 80. For photographs on a website, 75 to 82 is the practical range; the source has already been through one lossy codec, and pushing WebP quality above 85 mostly stores the HEIC's own compression noise. For images that will be shown large, or edited later, use 85 to 90.
A 4032x3024 iPhone photo of 1.9 MB as HEIC typically becomes 700 KB to 1.2 MB as WebP at quality 80. The same photo as JPG at the same setting would usually be 1.5 to 2.5 MB. At quality 70, WebP tends to land around 500 to 800 KB with only minor softening in fine texture. A screenshot-type HEIC of 400 KB usually ends up under 200 KB. These are typical outcomes rather than guarantees.
Resize before you publish, and keep the original
This page keeps the original dimensions, and a 4032 pixel wide image is far larger than any web layout needs. Converting alone gets you a smaller codec; resizing gets you the bigger win. If the destination is a web page, run the WebP through the compressor to bring it down to 1600 or 2000 pixels wide, or resize first and then convert. For the last few percent of savings on a site you control, HEIC to AVIF goes smaller still at the cost of slower encoding and narrower support.
Keep the HEIC as your master. It has more colour information and its metadata intact, and every lossy conversion discards something. Convert exported copies, not the library originals. Older desktop software and some email clients still cannot open WebP; for those, HEIC to JPG is the safe fallback. Multiple HEIC files can be dropped at once and are processed in order, each downloading on its own.