Why your logo gets a white box, why the converted file is bigger, and why iPhone photos won’t open on Windows. A practical guide to converting between PNG, JPG, WebP and HEIC.
Converting between image formats sounds trivial until something goes wrong — a logo comes back with a white box behind it, a converted file is somehow five times larger, or an iPhone photo will not open on Windows at all. The conversion itself is easy; knowing which direction to go, and what you lose along the way, is the part worth understanding.
JPG has no transparency. That single fact causes more conversion complaints than everything else combined. Convert a transparent PNG or WebP to JPG and those see-through areas must become a solid colour — white, in practice. Your logo ends up sitting in a white rectangle.
If you need transparency, your options are PNG or WebP. If you do not, JPG is usually the smallest sensible choice for photographs.
PNG to JPG is the right move when a photograph was saved as PNG. Expect roughly 60–90% smaller files, because PNG stores every pixel losslessly, which is wasteful for photographic detail while JPG is built specifically for it.
The savings evaporate on screenshots, flat graphics and text-heavy images — those can even grow, since PNG is genuinely efficient at large areas of uniform colour. And converting back later will not restore anything: JPG compression permanently discards data, so a round trip just gives you a larger file containing the same degraded image.
Since iOS 11, iPhones save photos as HEIC, which stores the same image in roughly half the space of a JPG. Apple devices handle it natively; Windows, older Android phones and most websites do not, which is why the file appears broken.
HEIC to PNG gives you a lossless copy — nothing is degraded, because PNG stores exactly what the HEIC decoded to. The trade-off is size: converting a photo this way commonly multiplies the file several times over.
For ordinary photo albums, JPG is usually the better destination. Choose PNG when you need lossless quality for further editing, or when the image contains text and sharp graphics.
JPG to WebP typically produces files 25–35% smaller at comparable visual quality. Across a page carrying a dozen photos that is a substantial saving, which translates directly into faster loading and better Core Web Vitals — the reason most performance audits recommend it.
A caveat: you are re-encoding an already-compressed image, so there is a small additional quality cost. It is usually invisible, but exporting WebP from your original source beats converting a JPG that has already been through compression once.
Sometimes you need to leave WebP behind. Images saved from websites are frequently WebP, and plenty of software still refuses it: older versions of Photoshop and Office, some printing services, certain photo frames and TVs, and upload forms that only accept JPG or PNG.
WebP to JPG trades some file size for universal compatibility. If your WebP has a transparent background, remember the rule above — convert to PNG instead, or you will get white where the transparency used to be.
| You want to… | Convert |
|---|---|
| Shrink a photo saved as PNG | PNG → JPG |
| Open an iPhone photo anywhere, losslessly | HEIC → PNG |
| Speed up a website | JPG → WebP |
| Use an image in software that rejects WebP | WebP → JPG |
For a mixed batch, the Image Format Converter handles up to 20 files at a time across PNG, JPG, WebP, AVIF, BMP and GIF, and hands the results back as a single ZIP.
Remember that JPG cannot hold transparency and most conversion surprises make sense. Use JPG for photographs, PNG for transparency and lossless quality, and WebP for anything going on the web. Every conversion here runs on a proper image engine with no watermark and no upload limit.