How the conversion works
Your browser decodes each JPG, turning it upright first if the camera stored it sideways. The page writes the pixels into a PNG and passes it through oxipng, which squeezes the file losslessly without touching a single pixel. The PNG has the same width, height and name as the JPG, with a .png ending.
IMG_2207.jpg → decode and apply rotation → write pixels to PNG → optimize losslessly → IMG_2207.png
Every step happens in your browser. The photos are not uploaded, and the optimizer, a small WebAssembly program, is downloaded once and runs on your device.
Be clear about what PNG can and cannot do
Saving a JPG as PNG is like photocopying a photocopy onto better paper: the copy will not fade any further, but it will not get sharper either. JPG compression happens when the JPG is first saved, and the detail it drops is gone. If your JPG shows blocky skies or fuzzy edges, the PNG will show exactly the same thing.
Good reasons to convert anyway
- Repeated editing. Every time you open a JPG, change it and save it as JPG again, it is compressed again and loses a little more. Work on a PNG copy and export to JPG once, at the end.
- Forms and tools that want PNG. Some sites, app stores, design templates and print-on-demand services ask for PNG files specifically.
- Transparency later. If you plan to remove the background or cut out a product, start from PNG so the result can keep its transparent areas.
- Screenshots and text saved as JPG. Converting stops further damage while you annotate or crop them.
If none of these apply, keep the JPG. It is smaller and opens everywhere.
Worked example: a product photo for a print-on-demand shop
Your print-on-demand store asks for PNG artwork and you have mug-design.jpg, 3000 × 3000 pixels and 1.4 MB. Drop it here and press Convert. You get mug-design.png, still 3000 × 3000, and the list shows how much bigger it is; for a detailed photo several times larger is normal. Upload that PNG. If you need the white background gone, run the PNG through a background remover next.
Size, metadata and limits
| JPG you drop in | PNG you get | |
|---|---|---|
| Pixels | As stored | Same, turned upright if needed |
| Compression | Lossy | Lossless, optimized with oxipng |
| Transparency | None | None yet, but supported |
| EXIF (GPS, date, camera) | Often present | Not copied |
Photos over about 16.7 megapixels are scaled down to fit the browser's canvas limit, and the list notes it. Optimizing a large PNG takes a few seconds per image, so a batch of 50 full-size phone photos will take a little while; press Stop whenever you like and the finished files stay ready to download.
Questions people ask
Will converting JPG to PNG make my photo look better?
No. The PNG is a pixel-for-pixel copy of the decoded JPG, so any blur, blockiness or color banding in the JPG is copied too. PNG cannot restore detail that JPG compression already discarded. What it does guarantee is that nothing more is lost from here on.
Why is the PNG so much bigger than the JPG?
JPG keeps photos small by throwing detail away. PNG is lossless, so it has to record every pixel exactly. For a typical photo the PNG is often several times the size of the JPG, even after the page runs it through a lossless optimizer. Screenshots and graphics saved as JPG grow less.
Does converting to PNG make the background transparent?
No. A JPG has no transparency, so the PNG starts out fully opaque. What PNG does is let you add transparency later: open it in an editor or a background-removal tool and the cut-out can be saved without a solid box behind it.
My photo was sideways in some apps. Will the PNG be?
No. Phones often store photos sideways with a note saying which way is up. This tool applies that note while decoding, so the PNG's pixels are already the right way round and it displays correctly everywhere.
Is the photo's location and camera data kept?
No. The PNG is a fresh file containing only the picture. EXIF data such as GPS location, date taken and camera model is not copied, which makes the PNG safer to share. Keep the original JPG if you need that information.
Are my photos uploaded?
No. Decoding, converting and the PNG optimizer all run in your browser. The images never leave your device.