PNG vs JPG vs WebP: Which Image Format Should You Use?
6 min read · Tools-Bench Learn
Every image you save has to pick a format, and the choice matters more than most people realize. The same photo can be 4 MB as a PNG, 400 KB as a JPG, and 250 KB as a WebP — with no visible difference on screen. Pick wrong and your website loads slower, your email attachment bounces, or your logo gets fuzzy edges.
The good news: the decision comes down to two questions. Is the image a photo or a graphic? And do you need transparency? Answer those and the right format is almost always obvious.
How each format compresses
JPG (or JPEG) uses lossy compression built for photographs. It divides the image into 8×8 pixel blocks and discards fine color detail your eye is unlikely to notice. This works brilliantly for photos, where colors shift gradually — but it smears hard edges, which is why JPG screenshots of text look blurry and why re-saving a JPG over and over degrades it a little each time.
PNG uses lossless compression: every pixel is preserved exactly. That makes it perfect for screenshots, diagrams, logos and any image with sharp lines or flat areas of color. The cost is size — a photographic PNG is often five to ten times larger than the equivalent JPG, because photographs have very little of the repetition that lossless compression relies on.
WebP, developed by Google, does both. Its lossy mode typically produces files 25–35% smaller than JPG at the same visual quality, and its lossless mode usually beats PNG by around 25%. It also supports transparency in both modes. Every modern browser has supported WebP since 2020, so the old compatibility objection is mostly gone.
The decision in practice
Here is the short version most images fall into:
- Photograph for the web → WebP (lossy), or JPG if the destination is old software or picky upload forms.
- Screenshot, diagram, or UI mockup → PNG, or lossless WebP if size matters.
- Logo or icon that needs a transparent background → PNG or WebP; JPG cannot do transparency at all.
- Image you will keep editing → PNG (lossless), so quality never degrades between saves.
- Email attachment or document insert → JPG; it is the most universally accepted format.
What about transparency?
Transparency is the hard constraint that eliminates JPG immediately. A JPG has no alpha channel — save a logo with a transparent background as JPG and the background becomes solid white (or black). PNG supports full 8-bit alpha, meaning each pixel can be anywhere from fully opaque to fully invisible, which is what makes drop shadows and anti-aliased edges look smooth over any background.
WebP matches PNG here and usually produces a smaller file. If a platform accepts WebP, it is the better choice for transparent images; if you are not sure, PNG is the safe default that everything from PowerPoint to ancient CMS installs will accept.
Quality settings: the 80% rule
For lossy formats, the quality slider is where most of the file-size savings live. Quality 100 is not "perfect" — it is just the least-compressed setting, and it wastes space. In practice, quality 75–85 is the sweet spot for photos: files shrink to a fraction of their original size while remaining visually indistinguishable at normal viewing sizes. Below about 60 you start seeing blockiness in smooth areas like skies and skin.
If you are preparing images for a website, combine a sensible quality setting with resizing. A 4000-pixel-wide photo from your phone displayed in a 800-pixel-wide article slot carries sixteen times more pixels than the reader will ever see. Resize first, then compress — the two together routinely cut files by 90% or more.
Converting without uploading your images
You do not need desktop software or a cloud service to switch formats. Tools-Bench's image converter runs entirely in your browser: the file is decoded and re-encoded on your own device and never uploaded to any server. That matters for private photos, unreleased product shots, or anything covered by an NDA — the privacy is architectural, not a policy promise.
Frequently asked questions
Is WebP always smaller than JPG?
Almost always at the same visual quality — typically 25–35% smaller for photos. Very small images or images that have already been heavily compressed can occasionally come out larger, so it's worth comparing when every kilobyte counts.
Does converting a JPG to PNG improve its quality?
No. Compression artifacts already baked into the JPG are preserved exactly by the lossless PNG — you get the same flawed pixels in a much larger file. Convert to PNG only to stop further loss from future edits.
What about HEIC, AVIF and other newer formats?
HEIC is Apple's camera format — great on-device, poorly supported elsewhere, so convert it to JPG or WebP before sharing. AVIF compresses even better than WebP and browser support is now broad, but many tools and platforms still don't accept AVIF uploads, so WebP remains the safer modern choice.