Got iPhone Photos as .HEIC? Convert Them to JPG With Your Wi-Fi Off (I Tested It)

A friend AirDrops you the photos from last weekend, or a relative emails them from an iPhone, and every file ends in .HEIC. Windows Photos asks you to buy an extension, the visa form says "JPG or PNG only", and the print shop's upload page just spins.

Search for a fix and you get a page of "free online HEIC converters". Nearly all of them work the same way: your photos go to their server, get converted there, and come back. For holiday snaps that may be fine. For photos of your kids, your ID or your home, with GPS coordinates baked into every file, it's worth knowing there's another way.

This guide converts HEIC to JPG inside the browser tab, and instead of just claiming "no upload", I checked it: I watched the network requests and then cut the connection halfway through. That test also showed one thing to wait for before you disconnect, so I'll show you exactly what to look for. The tool is PixSip (full disclosure: I make it).

The test photos

Five real iPhone photos, all CC0 from Wikimedia Commons: four from an iPhone 15 Pro Max and one from an iPhone 15. I saved them as HEIC and kept their original metadata, including GPS location on four of them. Four are 4032×3024 (12 MP, the iPhone's standard size) and one is a 24 MP shot at 5712×4284. Together they come to 17.2 MB.

Step 1: Open the converter and leave JPG as the only format

Go to PixSip's HEIC to JPG page. You don't need an account. The free plan takes up to 20 files per batch at up to 10 MB each, so full-size iPhone photos fit easily.

Under the drop area, the "Convert my images automatically" switch is already on and JPG is already selected. If the photos are going somewhere picky, like a government form, an older Windows PC or a print kiosk, leave it that way. You could add WebP or AVIF as well (the free plan writes up to three formats side by side), but for this job JPG is the format that opens everywhere.

You won't find a quality slider or a "target size" box. PixSip encodes at one quality setting that was calibrated against TinyPNG, and the size reduction you'll see below comes entirely from that.

Step 2: Wait for the lock icon, then (optionally) try one photo

Give the page a few seconds after it opens. It downloads the HEIC decoder, the JPEG encoder (a WebAssembly build of MozJPEG) and the ZIP helper straight away, and the drop area stays disabled until they're ready: the small spinner under "Drop images here" turns into a 🔒. Once you see the lock, you can disconnect before converting anything. In a retest on 11 October, five HEICs converted with the network off from the very start.

If you'd like to see it work before you disconnect, convert one photo while you're still online. I used the frog shot: 2.4 MB of HEIC became a 981.5 KB JPG (−60%) in about five seconds.

I also logged every request the tab made during that conversion. It downloaded PixSip's own script files and mozjpeg_enc.wasm. The only thing it sent out was an analytics ping of roughly 1 KB. Nothing anywhere near the size of a 2.4 MB photo left the machine.

Step 3: Turn the Wi-Fi off and drop the rest

With the lock icon showing, disconnect: switch off Wi-Fi, unplug the cable, or turn on airplane mode. Then drag the remaining photos onto the page. Mine (four HEICs, 14.8 MB) finished in about 15 seconds with no connection at all:

Photo	Size (px)	HEIC	JPG	Saved
IMG_FROG (converted online, step 2)	4032×3024	2.4 MB	981.5 KB	−60%
IMG_ALCATRAZ	4032×3024	2.6 MB	689.8 KB	−73%
IMG_BALLPARK	5712×4284	6.3 MB	1.6 MB	−74%
IMG_BISTRO	4032×3024	3.3 MB	635.9 KB	−81%
IMG_SHIP	4032×3024	2.6 MB	666.3 KB	−74%
Total		17.2 MB	4.6 MB	−73%

PixSip's own summary says the same thing: "Saved 12.6 MB total · 73% smaller". Nothing was resized, so every JPG has exactly the same pixel dimensions as its HEIC. Your results will vary with the photo. A busy, detailed scene like the frog in the grass saves less than a plate on a white tablecloth, and an HEIC that was already heavily compressed can occasionally come out larger as a JPG. If that happens, add WebP as a second format and keep the smaller file.

Step 4: Check the detail before you send anything

Click Compare on any row. You get a slider with the decoded original on the left and the JPG on the right, each labeled with its size. Here's the bistro photo, which shrank the most (3.3 MB → 635.9 KB):

The full-frame view can hide problems, so I also cropped the same 640×640 patch from both files at 100%, pixel for pixel, with no scaling:

The char on the steak, the grain of the meat and the edge of the watercress all survive. If you want to inspect fine detail yourself, the compare view has a Zoom 1:1 button.

Step 5: Save the JPGs one by one or as a ZIP

The orange JPG button on each row saves that one file, and it works offline. I saved the frog JPG with the network still off.

Download 5 as ZIP works offline too, because the ZIP helper now loads with the page. In the 11 October retest the archive downloaded with the network still off. It contained IMG_FROG-compressed.jpg and the other four files. The archive is built in the tab, so this step doesn't upload anything either.

What's actually in the JPGs

I opened the five output files in Python to check two things:

• Dimensions: all unchanged (4032×3024 ×4, 5712×4284 ×1).
• Metadata: gone. Four of the HEICs carried GPS coordinates and all five named the phone model. None of the JPGs has GPS, camera model or any other EXIF field.

For photos you're about to send to a stranger or post publicly, stripping the location is a feature. If you need the date and place later for your own records, keep the original HEIC files.

If you only need to look at the photos

If the photos just have to open on your own PC, converting may not be the best fix. This guide to opening HEIC files on Windows without converting them compares Microsoft's extensions with changing the iPhone's camera setting. And if you're wondering why the tool was built to run locally in the first place, the reasoning is in why PixSip keeps your images on your device. Batches bigger than 20 photos or 10 MB per file need one of the paid plans.

One more tip: if one of these photos is headed for a square profile picture, squareimage.dev pads it to 1:1 without cropping anyone out.

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Related PixSip guides on other platforms: HEIC to JPG, WebP and AVIF in one drop (DEV.to) · Compress JPGs before uploading them to WordPress (Medium) · WebP vs AVIF: which is actually smaller? (DEV.to)