Choosing the Right Image Format: PNG, JPG, WebP, AVIF and SVG

Lossy formats discard visual data to shrink the file. They model a limit of human vision: remove the detail an eye is least likely to notice, and the file gets dramatically smaller. This works extremely well for photographs, where every pixel is a measurement and small deviations read as imperceptible. It works badly for text, logos and flat-colour graphics, where a small deviation shows up as a smear around every hard edge.

Lossless formats keep every byte of information and compress it the way a ZIP does — by finding redundancy, not by deleting it. The file is always exactly reconstructable, but it is larger. For screenshots, diagrams, logos and anything you will edit again later, that is the correct trade.

Transparency is not universal. PNG, WebP, AVIF, GIF and SVG all carry an alpha channel; JPG does not have one at all, so converting a transparent PNG to JPG fills those pixels with a solid background colour — usually white or black, depending on the tool. If the transparency matters, either stay on a format that supports it or decide explicitly what the background should become.

Animation is narrower still. GIF is the historical standard, but WebP and AVIF both support animation at a fraction of the size, and PNG has its own APNG variant. A JPG is always a single still frame.

Colour depth matters for medical, satellite and photographic work. PNG and TIFF carry 16 bits per channel; JPG and most WebP/AVIF output is 8-bit. Converting 16-bit to 8-bit is irreversible — gradients that were smooth can develop visible banding.

Use JPG for photographs shared at a fixed size: web heroes, social posts, email attachments. Use PNG for screenshots, logos, line art and anything with text in it. Use WebP or AVIF when the image is going onto a web page and you want both quality and a small payload — both routinely beat JPG by 25–50% at the same visual quality, which is why browsers and CDNs moved to them. Use SVG for logos, icons and diagrams that need to stay sharp at every size, and for anything a designer will want to edit as shapes rather than pixels.

GIF survives mostly for animation and for the specific aesthetic of its 256-colour palette. For new work, an animated WebP or a short MP4 is usually smaller and better looking. BMP and TIFF remain relevant for raw interchange and printing pipelines, not for delivery.

Convert when the destination imposes a constraint: a CMS that only accepts JPG, a print shop that wants TIFF, a website that should serve AVIF with a JPG fallback, a colleague on software that does not open WebP. Converting to a strictly smaller lossy format is also worth it when bandwidth is the bottleneck and the image is going to be viewed once.

What you should not do is chain conversions. Saving a JPG as WebP and then as JPG runs the lossy compression twice, and the second pass compresses the artefacts of the first. Always convert from the original file, not from a previous export.