Image formats explained: PNG, JPEG, WebP and friends
Every image format is a trade. PNG is lossless and supports transparency, but heavy. JPEG is small and universal, but lossy and allergic to sharp text. WebP beats both on size with transparency intact. GIF is a relic that refuses to die. AVIF compresses best of all, with patchier tooling support.
Picking right matters more than ever: images are the bulk of most pages, and Google's Core Web Vitals directly punish heavy ones. Converting a hero image from PNG to WebP routinely cuts its weight by a third — the same visual, a faster site.
Open the free Image Format Converter — no signup, runs entirely in your browser.
How to use it
- Drop in a PNG, JPEG, WebP, GIF, BMP, AVIF or ICO file.
- Choose the output format — PNG, JPEG or WebP — and set the quality.
- Optionally resize by longest side, then download and compare the file sizes.
Why this one
- Seven input formats, three optimized output formats.
- Quality slider from 1 to 100, plus lossless WebP mode.
- Resize by longest side in the same pass — no second tool needed.
- Background color control when flattening transparency to JPEG.
Frequently asked questions
Which image format is best for websites?
WebP for almost everything: 25-35% smaller than JPEG or PNG at equal quality, transparency support, and 97%+ browser coverage. Use AVIF when you control the pipeline and want maximum compression.
Does converting an image reduce its quality?
Converting to a lossy format (JPEG, lossy WebP) discards some detail — at 80-90% quality it is invisible for photos. Converting to PNG or lossless WebP keeps every pixel exactly as decoded.
What happens to transparency when converting to JPEG?
JPEG has no alpha channel, so transparent areas get flattened onto a background color — you pick which. If transparency matters, choose PNG or WebP instead.