Two things get lost in this conversion, and both catch people out, so they are worth saying immediately. Animation does not survive — you get the first frame. Transparency does not survive either — JPEG has no alpha channel, so transparent pixels are filled with a solid colour. If either of those matters to you, converting to PNG instead will keep the transparency, though nothing keeps the animation.
Why this is often the wrong conversion
GIF and JPEG are bad at opposite things, and stacking them compounds the damage. GIF has already reduced the image to 256 colours, usually with dithering — fine speckles of two colours used to fake a third. JPEG is specifically poor at fine, high-contrast detail, which is exactly what dithering is. The encoder spends bytes reproducing the speckle pattern and then blurs it anyway, so you can end up with a JPEG that is both larger than expected and visibly worse than the GIF.
PNG is usually the better target from a GIF: it is lossless, it keeps transparency, and for palette-style images it is often smaller than the JPEG would be.
When JPEG genuinely is the right answer
- The GIF is a photograph rather than a graphic, and you need it in the format an upload form or print service accepts.
- You are pulling a still frame out of an animation for a thumbnail or preview.
- The destination flatly refuses PNG and GIF, which some older systems do.
- The GIF is large and you need the file size down more than you need fidelity.
Choosing a quality setting
Go higher than you normally would — 90 or above. The dithering in a typical GIF acts like noise, and JPEG at moderate quality turns noise into visible mush. A high setting costs bytes but keeps the result recognisably close to what you started with. If the GIF is a flat graphic or logo with no dithering, moderate settings are fine, though PNG would serve you better still.
The transparent background question
GIF transparency is binary — a pixel is either there or it is not — so a transparent GIF converted carelessly ends up as a hard-edged shape on a black rectangle. Pick the fill colour above to match wherever the image is going. Because GIF edges are already stair-stepped rather than smoothly anti-aliased, you may still see a slight fringe where the old background colour bled into the edge pixels.
All decoding and encoding runs on your own device inside this tab, with nothing transmitted anywhere.