Why you must pick a background
An SVG is usually see-through where nothing is drawn. A JPG cannot be see-through at all, so the converter has to put something behind the drawing. It fills the picture with your colour before the drawing is placed on it, and soft edges blend into that colour.
This decides whether the result looks right. A dark logo on a transparent background works on white. A white logo does not, because it turns into white on white, and needs a dark or coloured background. Rounded corners in the SVG become corners of the background colour, not transparent corners. When you need to keep transparency, use SVG to PNG.
Vector art in a photo format
JPG was made for photographs. It works on small blocks and discards detail that a camera picture does not need. Vector art is the opposite: sharp edges, flat colour, thin lines. In JPG those edges pick up faint noise and slight blur.
We measured it. A small test drawing converted at 512 pixels wide matched the exact composite within one or two levels of 255 in its flat areas, but at the edges the difference rose to 77 levels at the worst pixel. The same flat logo was 4.6 KB as a PNG and 8.4 KB as a JPG, almost twice as large.
Detailed illustrations, gradients and drawings that include photographs go the other way. An 800 by 600 illustration made of 40 overlapping gradient circles, from an SVG of 9.4 KB, was 177 KB as a PNG and 33.7 KB as a JPG. An SVG with a photograph embedded in it (38.7 KB) gave a 30.0 KB JPG and a 167 KB PNG. They are smaller as a JPG, and the faint blur at edges does not show.
Settings for text and logos
- Quality 95 or more keeps colour at full detail instead of half detail. Coloured text on a flat colour stays cleaner.
- A bigger width helps with edges. Drawing at 2048 pixels and shrinking in the place where you use the picture gives smoother edges than drawing small. It also sets the file size: the gradient illustration was 18.8 KB at 512 pixels wide, 33.7 KB at its own 800 pixels and 108 KB at 2048 pixels.
- Pictures inside the SVG are drawn when they are embedded as data. A test SVG with an embedded PNG drew it correctly, and a red square measured 220, 40, 41 in the JPG. A photograph embedded in an SVG does not get sharper at a larger width, because it is still the same pixels: at 2048 pixels wide that SVG gave a 277 KB JPG with no new detail. Pictures linked by address are not fetched.
- Fonts come from your device, as they do for any SVG drawn as an image. A font that is not installed is replaced by a default one, so convert text to outlines first when the lettering must be exact. SVG to PNG explains this in detail.
Check one result before you convert a whole batch. The list shows the size of each JPG next to the size of the SVG.
When a JPG is the right format
Use JPG when a site or program accepts only JPG, when you place the picture on a photo-like background, or when the drawing is detailed and a PNG would be large. Many forms for ID photos, product listings and print orders ask for JPG.
Do not use it for logos you will resize again, for pictures with transparency that you want to keep, or for line art with small text. Keep the SVG as your master and make a JPG for each purpose.