What an SVG file actually is
SVG is not a grid of pixels at all: it is an XML document describing shapes, paths and text, which the renderer draws at whatever size it is asked for. That is why a 4 KB logo stays perfectly sharp on a billboard, and why the file is often smaller than a thumbnail of itself.
SVGs come out of Illustrator, Figma, Inkscape and icon libraries. Logos, icons, charts and diagrams are the natural cases — anything built from shapes rather than captured from a camera.
What you get from JPG
Saving as JPEG re-encodes the image with lossy DCT compression at a quality level you choose. Around 80% is the usual sweet spot: files shrink dramatically and the difference is invisible at normal viewing sizes.
Nothing in mainstream computing fails to open a JPEG. Thirty-year-old software, print shops, hospital systems, government upload forms, every phone and every browser — if a system takes images at all, it takes JPG.
What changes when you convert SVG to JPG
This is where the file size actually drops. A SVG stores its image without discarding anything; JPEG works in 8×8 blocks and throws away the fine detail inside each one, then usually halves the colour resolution as well through chroma subsampling. Photographs take that treatment invisibly. Flat colour, text and sharp edges do not — they are where the block boundaries and coloured fringing show up, so keep the quality high if the image contains any.
Transparency is the thing to watch. SVG can store transparent areas and JPG cannot, so anything see-through is composited onto a white background during conversion. A logo with soft edges will show a white fringe when placed on a coloured background afterwards. If the transparency matters, convert to PNG or WebP instead.
The important loss here is scalability rather than quality. An SVG is drawn fresh at whatever size it is asked for; the moment it becomes a JPG it is a fixed grid of pixels, and enlarging it later softens the edges. Rasterize at the largest size you will realistically need, and keep the original SVG — it remains the master copy.