Does converting HEIC to JPG lose quality?

People hesitate before converting photos they care about, and that’s a sensible instinct. A converted photo is a new file made from the old one, and with JPG, making a new file always involves some compression. The question is how much that matters in practice.

Two kinds of compression

Both HEIC and JPG are lossy. When the phone saves a photo, it throws away fine detail that eyes are bad at noticing, such as tiny shifts in color within a small patch. HEIC does this with a newer, cleverer method, the same one used for modern video, so it can keep the same look in about half the space.

Converting means decoding the HEIC back into plain pixels and saving those pixels as a JPG. The JPG save does its own round of discarding. So you lose twice: once when the phone saved the HEIC, which already happened and can’t be undone, and once more when the JPG is saved.

How much is lost

At a high quality setting, the second loss is small. JPG at 90% keeps nearly everything you can see when the photo is viewed at a normal size. If you zoom far into a smooth area, such as a clear sky, you might find faint blockiness or slight color banding that wasn’t there. On a phone screen, a monitor or a normal print, people generally can’t tell the two apart.

At lower settings the loss becomes visible. Below about 70%, edges start to show halos and fine textures turn to mush. That’s why the HEIC to JPG tool offers only three settings, all at 80% or above:

• Best (95%) for photos you’ll print large, crop heavily or edit.
• High (90%) for almost everything else, and the default.
• Smaller (80%) for quick sharing where file size matters more than fine detail.

Why the JPG is usually bigger

It feels backward: you lose a little quality and get a bigger file. But it follows from how the formats work. HEIC’s method is about twice as efficient, so the same look costs JPG more bytes. A 2 MB HEIC often becomes a 3 to 5 MB JPG at high quality.

If the size is a problem, for an email or a form with a limit, convert first and then use the compressor to bring the JPG down to a target size.

When to choose PNG

PNG is lossless: it stores every pixel exactly. Converting HEIC to PNG adds no further loss at all. The price is size. Photos have millions of slightly different colors, which lossless formats store poorly, so a PNG of a phone photo can easily be 15 to 30 MB.

PNG makes sense when you’ll edit the photo and save it several times, since each JPG save would lose a little more. For uploading and sharing, JPG is the better choice.

Things other than pixels

Quality isn’t only about the picture. A converted copy also differs in a few ways that people notice later.

• Brightness range. Many recent phones save photos with extra brightness information for screens that can display it. A standard JPG doesn’t carry that, so on such screens the converted copy can look a little flatter in the highlights. On most other screens it looks the same.
• Metadata. The tool’s copies leave out location, date and camera details. That’s good for privacy, but photo apps may sort the copy by the day you made it.
• Orientation. Phones often store photos sideways with a note on which way is up. The tool turns the picture upright before saving, so the JPG shows correctly everywhere, even in programs that ignore those notes.

The safe habit

Treat the HEIC as the original and the JPG as a copy for a purpose. Keep the original where your photos live, convert copies when a site or person needs them, and convert again from the original if you need a different quality later. Converting from a converted copy stacks the losses. Converting from the original never does.