Dedicated, format-locked workflow
Convert PNG to JPG with predictable transparency handling
Prepare widely compatible photo files while choosing exactly how transparent PNG pixels are flattened.
Conversion settings
Compatible photo output; transparent pixels use your selected background.
Locked: PNG → JPG / JPEG
Drop images here or choose files
PNG input only · 50MB each · 20 files per batch
Why this workflow exists
JPG is accepted by most photo upload forms and email workflows.
Photographic PNG files can often become substantially smaller as JPG.
Some older software and print workflows handle JPG more predictably than PNG.
What PixelConvert does with a PNG file
The server verifies the PNG signature, decodes the image including its alpha channel, composites any transparent pixels onto the background colour you selected, and encodes a JPEG at your chosen quality. Everything happens in memory and nothing is retained afterwards.
The background choice is presented explicitly rather than defaulting silently to white, because the correct colour depends on where the image will be placed and the decision cannot be undone once the JPEG is written.
Transparency is flattened, permanently
JPEG has no alpha channel. This is not a quality setting that can be tuned — the format simply has nowhere to store the information. Every transparent pixel must be given an opaque colour before encoding, and whatever colour is chosen becomes part of the image forever.
Partially transparent pixels are where this bites hardest. The antialiased edge around a shape, a soft shadow, or a glow consists of pixels that are part-way between opaque and transparent. Those get blended with the background colour, so the edge is not merely placed on the wrong background — it is fringed with it, and no later editing cleanly removes the fringe.
Choosing the right background colour
Match the colour to the destination. A logo going onto a white page should be flattened onto white. The same logo going into a dark header should be flattened onto that dark colour. Flattening onto the wrong one produces a visible rectangle around the mark.
If you do not yet know where the image will be placed, this conversion is premature. Keep the PNG until the destination is decided, because the PNG retains the flexibility that the JPG gives up.
When JPG will not be smaller
The expectation that JPG shrinks files holds for photographs and fails for flat graphics. Our measured counterexample: a 1200×630 sharp-text image was 33,657 bytes as optimized PNG and 49,875 bytes as JPEG at quality 70 — larger, and with visibly degraded text.
Our transparent logo showed the same pattern: 11,839 bytes as PNG against 20,404 bytes as JPG, and the JPG also lost the transparency. If your PNG is a screenshot, a diagram, an interface graphic, or anything with sharp text, converting to JPG is likely to make it both bigger and worse.
Verified format differences
| Property | PNG source | JPG / JPEG result |
|---|---|---|
| Compression | Lossless | Lossy, adjustable quality |
| Transparency | Full alpha supported | Flattened to selected color |
| Sharp text | Preserved exactly | Softened by lossy encoding |
| Best fit | Graphics and editing | Photos and broad compatibility |
How to use PNG to JPG
- Step 1Add genuine PNG files.
- Step 2Choose a quality and background color.
- Step 3Convert and inspect fine text and transparent edges before using the JPG.
Good use cases
- Emailing a photographic PNG
- Meeting a JPG-only upload rule
- Flattening an asset onto a known white or branded background
Limitations to check
- JPG cannot store transparency; transparent pixels are flattened to your chosen color.
- JPG compression is lossy and can soften sharp text or interface graphics.
- For flat graphics, the JPG output may be larger than the PNG source as well as visibly worse.
Questions answered
- What happens to transparent pixels?
- They are composited onto the color you choose before JPEG encoding. The choice is permanent in the output, which is why it is presented explicitly rather than defaulted.
- Is JPG always smaller?
- No. It is usually smaller for photographs and frequently larger for flat graphics. Our sharp-text test measured 33,657 bytes as PNG against 49,875 as JPEG quality 70.
- Which background colour should I choose?
- The colour of wherever the image will be displayed. White for a white page, the header colour for a dark header. If you do not know yet, keep the PNG until you do.
- Why does my logo have a coloured fringe?
- Its antialiased edge pixels were partially transparent and got blended with the background colour. Converting again with the correct colour fixes it; editing the JPG afterwards does not.
- Can I get the transparency back?
- Not from the JPG. The alpha channel is gone and the flattened colour is baked into the pixels. Keep the original PNG.
Troubleshooting PNG to JPG
There is a white box around my logo now
Why: Transparent pixels were flattened onto white, and the destination background is a different colour.
Fix: Re-convert from the original PNG with the background colour set to match the destination.
The text in my screenshot looks fuzzy
Why: JPEG compresses sharp high-contrast edges badly; text is the worst case for it.
Fix: Keep it as PNG. Screenshots and graphics with text belong in a lossless format.
The JPG came out larger than the PNG
Why: The content is flat graphics rather than photographic, which is the case where PNG compresses better.
Fix: Stay with PNG. Our measured test showed 33,657 bytes as PNG against 49,875 as JPEG q70 for the same image.
The edges of my shape have a coloured halo
Why: Semi-transparent antialiasing pixels were blended with the background colour.
Fix: Convert again using the exact destination background colour, or keep the PNG so the edges stay clean.