PNG to JPG Converter

What this tool is used for

• Shrinking a photographic PNG that is far larger than it needs to be for the web.
• Producing a JPEG for a system or a form that will not accept PNG.
• Trading a controlled amount of quality for a size budget using the quality slider.
• Flattening an image with transparency onto a background for a context that cannot handle alpha.
• Preparing a photo for an email attachment where size limits apply.

Frequently Asked Questions

What happens to transparency?

It is destroyed — JPEG has no alpha channel, so transparent pixels are composited onto a background colour, usually white or black. A logo with a transparent background acquires a solid rectangle, which is the most common surprise here.

When is this conversion a good idea?

For photographic content saved as PNG, where JPEG can be 5-10x smaller with no visible difference. For screenshots, logos, line art or anything with text it is a bad trade — JPEG's artefacts show badly on sharp edges.

Why does text look fuzzy afterwards?

Because JPEG uses chroma subsampling and block-based DCT compression, both of which blur high-frequency detail. Text is exactly that, so ringing artefacts appear around every letter — visible even at high quality settings.

What quality should I choose?

75-85 covers most uses. Above 95 the file grows sharply for almost no visible gain; below 60 blocking artefacts become obvious. There is no universally right number, since it depends on the image content.

Is the conversion reversible?

No. Converting the JPEG back to PNG preserves the compressed pixels exactly but recovers nothing — the discarded detail and the transparency are both gone. Keep the PNG as the master.

What colour replaces transparency?

Whatever the converter composites against — usually white, sometimes black. This is why a logo designed for a dark background converts to something with a white box around it, and why the choice should be explicit.

Does chroma subsampling affect the result?

Noticeably on saturated edges. JPEG commonly stores colour at half resolution, which smears the boundary between two strong colours — most visible on red text, and the reason some encoders offer 4:4:4 for graphics.

Common errors and gotchas

• Converting a screenshot or a diagram, where JPEG's artefacts around text and sharp edges are very visible.
• Losing transparency, which becomes a solid fill — often black — rather than staying transparent.
• Choosing maximum quality and getting a file larger than the PNG was.
• Iterating by re-saving the JPEG repeatedly, which compounds loss at every step.
• Assuming a smaller file is always better, when the artefacts undermine what the image was for.