When to Convert JPG to PNG (And When You're Wasting Bytes)
If you're converting a JPG to a PNG hoping the image will get better, you're going to be disappointed. JPG is lossy — the original detail was thrown away when the file was first saved as a JPG. Converting to PNG just locks the existing quality in a bigger box.
That said, there are two real reasons to do the conversion. Knowing which one applies to you is the difference between a useful 10-minute fix and a folder full of pointlessly-large files.
Reason 1: you need transparency
JPG has no alpha channel. Every pixel is opaque. If you have a JPG of a logo, a product cutout, or a sticker, and you need it to sit on a coloured background or website without a visible square around it, JPG won't do it — you need PNG.
But here's the catch: converting an existing JPG to PNG does not add transparency. The JPG already has whatever background was baked into it (usually white). The PNG you get is a same-size file with that white still in place.
To actually get a transparent background you need two steps:
- Convert JPG to PNG using Bulk Image Converter
- Remove the background using Background Remover or a manual editor
If your goal is "transparent product shot for a website", skip step 1 — the background remover takes a JPG directly and outputs a transparent PNG in one step.
Reason 2: you're going to edit further
If a JPG is going through several rounds of edits — crop, colour-grade, resize, paste over something — every save back to JPG drops a little more quality. Each save re-applies the lossy compression on top of the previous lossy compression. By round five you'll see banding in skies and crunchiness around edges.
Convert to PNG once at the start of the editing chain, do all your work in PNG, and only re-export to JPG at the very end. The intermediate PNG files are big, but lossless. You'll throw them away when you're done.
This matters less if you're using a tool that keeps the source untouched and only re-encodes JPG once at export (most modern photo editors do this). It matters a lot if you're doing manual round-trips through different tools.
Convert in your browser
Buncha's Bulk Image Converter takes JPG in and writes PNG out. Drop one or fifty; pick PNG; download. Browser-only — your image never uploads.
The conversion uses your browser's <canvas>: decode the JPG, paint to canvas, export PNG. No quality loss in the conversion itself (JPG → PNG is information-preserving). Whatever the JPG had, the PNG keeps.
Reasons that aren't real reasons
- "PNG is better quality" — only if the source was already lossless (a screenshot, a graphic, a vector export). For a photo, the JPG already lost detail. PNG just preserves what's left.
- "PNG is more universal" — both formats work everywhere. PNG isn't more compatible than JPG.
- "PNG is sharper" — only when the original was sharp (graphics, text). A blurry JPG converted to PNG is still a blurry image.
File size — expect bigger
Photos converted from JPG to PNG are typically 5–10× larger. A 200 KB JPG becomes a 1.2 MB PNG. There's no compression magic to fix this — PNG just stores the raw pixel data losslessly. If size matters, stay JPG.
Bulk works the same
Drop a folder of JPGs into the bulk converter; it processes them one at a time and offers a single ZIP download with all the PNGs.
The shortest path
If you actually need transparency, skip JPG→PNG and go straight to Background Remover. If you need the lossless intermediate for further editing, the bulk converter handles it. Otherwise, you're probably better off keeping the JPG.