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Your iPhone takes beautiful photos, but the moment you try to email one, post it to a forum, or open it on Windows, you hit a wall: "HEIC files are not supported." Here's why HEIC exists, why it's a problem, and how to convert it to JPG or WebP in seconds without uploading a single photo to anyone's server.
The short version: Drop your HEIC files into Saint Web Image, choose JPG (or WebP) as the output format, and click Convert. Everything happens in your browser, your photos never leave your device.
HEIC stands for High Efficiency Image Container. It's a wrapper around HEVC (also known as H.265), the same video compression standard used for 4K Blu-rays, applied to still images. Apple adopted it as the default iPhone camera format starting with iOS 11 in 2017.
The appeal is straightforward: HEIC files are roughly half the size of equivalent JPEGs at the same visual quality. For a phone that holds tens of thousands of photos, that adds up to gigabytes saved.
The trouble is that HEIC support outside the Apple ecosystem is patchy:
<img> tag.If you've ever tried to send a photo to a Windows-using relative and watched them give up, you know the pain.
Search "HEIC to JPG converter" and you'll find dozens of websites. Almost all of them work the same way: you upload your photo, their server converts it, and you download the result.
That's a problem for a few reasons:
Modern browsers ship with everything needed to decode HEIC and re-encode it as JPG, PNG, WebP, or AVIF. Saint Web Image uses three pieces of standard web technology:
heic2any library decodes HEIC into raw pixel data.OffscreenCanvas and a Web Worker handle the encoding off the main thread, so your browser tab stays responsive even when converting 50 photos at once.canvas.convertToBlob() produces the final JPG, WebP, or AVIF output entirely in memory.Result: your files never travel anywhere. They go from the file picker into your browser's memory, get converted, and come back out as a download, without ever touching the network.
Both work everywhere now, so the question is really about what you're going to do with the photos:
| Use case | Best format | Why |
|---|---|---|
| Sharing with family on Windows | JPG | Universal compatibility, opens in any photo viewer |
| Uploading to a website you own | WebP | 25–35% smaller than JPG, faster page loads |
| Posting to social media | JPG | All platforms accept it; some still re-compress WebP |
| Email attachments | JPG | Works in every email client without exception |
| Archiving photos | PNG or original HEIC | Lossless, no quality loss on each save |
If you're tired of converting every photo, you can switch your iPhone back to JPEG:
From now on, new photos will save as JPEG. The trade-off is that your photos will take up roughly twice the storage on your device. For most people that's a fair price for never thinking about HEIC again.
HEIC (High Efficiency Image Container) is the default photo format on iPhones and iPads since iOS 11. It uses HEVC compression to store images at roughly half the file size of JPEG with similar visual quality.
HEIC is a newer format and isn't supported by every operating system, browser, or app. Windows 10 and 11 require a paid extension from Microsoft, and most websites and chat apps don't accept HEIC uploads, that's why converting to JPG or WebP is often necessary.
It depends on the converter. Most online tools upload your photos to a server, where they may be stored or processed by third parties. Saint Web Image converts everything in your browser using a Web Worker, your files never leave your device, so it's the safest option for private photos.
JPG uses lossy compression, so any conversion involves some quality loss. With Saint Web Image's quality slider set to 90 or above, the difference is virtually invisible to the human eye while keeping file sizes reasonable.
Open Settings → Camera → Formats and select "Most Compatible". New photos will then save as JPEG instead of HEIC. Existing HEIC photos will remain in their original format.
HEIC is great for what Apple designed it for, efficient on-device storage. It's a poor fit for sharing across the wider web, where JPG and WebP still rule. Whenever you need to convert, do it in your browser. It's faster, more private, and there's no upload limit.