Why Your Transparent PNG Turns Black When Converted to JPG

You converted a PNG with a transparent background to JPG and the transparent areas turned solid black. This is not a bug — JPG simply does not support transparency. Here is exactly what happens and how to fix it.

JPG has no alpha channel

PNG supports an alpha channel — a layer of data that tells each pixel how transparent it is. JPEG does not have this concept. When you convert PNG to JPG, the converter has to fill those transparent pixels with something.

Many tools default to black (RGB 0,0,0) because that is what an empty canvas looks like in memory. The transparent pixels become black pixels. This is especially noticeable with logos, icons, and product photos with cutout backgrounds.

How to get a white background

A good converter composites the transparent image onto a white background before encoding to JPEG. MiniPx does this automatically — when you convert PNG to JPG, transparent areas become white, not black.

If you need a specific background colour, add it in an image editor before converting. Or keep the file as PNG or WebP if you need to preserve transparency.

When to keep PNG instead

If your image needs transparency (logos on coloured backgrounds, overlays, UI elements), do not convert to JPEG. Stay with PNG or switch to WebP — both support alpha channels. Only use JPEG for photographs and images where transparency is not needed.

Related reading: PNG compression guide · Best format for websites · AVIF vs WebP vs JPEG