Which format is smallest
Which format is smallest encodes PNG, JPEG, WebP, and AVIF from one drop and lists the sizes. Download any of them. It is not a beauty contest and it does not pick for you — auto-optimize does that.
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Utilities
Compare how small JPEG, PNG, WebP, and AVIF get from the same image, in the browser. Nothing is uploaded.
Runs in your browser · Nothing uploaded
About Utilities
Most format arguments on the internet are vibes. This page encodes the same pixels several ways and prints the sizes. You can download whichever you actually need. It is a measurement, not a sermon about the one true web format.
Quality is matched for the lossy formats. PNG is lossless, so it is the honest baseline for “what does this picture weigh without throwing anything away.” A two-colour icon and a noisy camera JPEG will not agree, which is why the table exists.
Video shootouts belong on a desktop encoder for long clips. This utility is stills. Format hubs link here because “which container is smallest” is the question after “can I convert.” Nothing is uploaded; the encodes run in this tab.
Tools in this category
Common questions
Why is PNG always the largest?
On photographs, usually. PNG is lossless. JPEG/WebP/AVIF throw away detail on purpose. On a two-colour icon, PNG can win. Look at the table instead of assuming.
Is the smallest file the one I should use?
On a website, often. In an archive, no. AVIF that is tiny and slightly mushy is a delivery format. Keep the original if you still edit.
Does this upload the image to compare it?
No. Four encodes in the tab. The network tab should stay boring. If you see a POST of the photo, that is not this site.
Where do I go after I pick a format?
The matching convert pair, or compress if you already have that container and only want it smaller. Auto-optimize if you want the smallest of JPEG/WebP/AVIF without looking.
Why these tools don't upload your files
There is no server to upload to. Each page is a static file, and the work happens in your browser. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network and it keeps working. The longer explanation