How is compression different from resizing?

Compression keeps the pixel dimensions and re-encodes the data at lower quality; resizing reduces the number of pixels. They multiply: resize to the size the image will actually be displayed at, then compress, and you'll get the smallest files. One note — this tool does cap very large images at 4096 pixels on the longest side, scaling them down if needed, since images beyond that are almost never displayed at full resolution.

Why doesn't my PNG shrink as much as a JPG?

PNG is a lossless format, so there's less room to trade quality for size. Screenshots and graphics with flat colors still compress well; photographic PNGs don't. If transparency isn't needed, converting a photographic PNG to JPG or WebP (with the Convert tool) saves far more than recompressing it as PNG.

What if the result isn't smaller?

Occasionally a file is already optimally encoded — re-encoding it can't help and the tool reports 'no size reduction'. This is common with images that have already been through a compressor. Lowering the quality slider or reducing dimensions with the Resize tool are the remaining levers.

Will I see the quality loss?

At 80% quality, almost never at normal viewing sizes. At 60% you may notice slight softness or artifacts around hard edges in photos. Text-heavy screenshots show artifacts sooner than photographs, so keep those at higher quality or leave them as PNG.

Compress Image

Reduce image file size while maintaining quality.

Drop image files here or browse

Max 50MB per file · Up to 20 files

About Compress Image

Compressing images is the single most effective optimization for almost any website or email — images typically account for well over half the bytes on a page. Convertora's compressor re-encodes JPG, PNG, WebP, and AVIF files at a lower quality setting and works toward a target file size you choose, routinely cutting 50-90% off photographs with little visible difference.

Under the hood the tool uses the browser-image-compression library running entirely in your browser. It decodes the image, re-encodes it at your chosen quality, and iterates until the result fits under your size cap. Because nothing is uploaded, you can compress private photos, scanned documents, and client material without them ever touching a server, and a batch of twenty files takes seconds rather than a round-trip per image.

How to use it

1Drop up to 20 images into the upload area (50 MB per file).
2Set the quality slider. 80% is a sensible default; 60% is aggressive but still acceptable for most photos viewed at normal size.
3Set the maximum output size per image, from 0.1 to 10 MB. The compressor lowers quality in steps until each file fits under this cap.
4Click Compress. Each image is re-encoded and downloaded with a '-compressed' suffix, keeping its original extension.
5Check the summary line comparing total original and compressed sizes, with the percentage saved.

Common use cases

Optimizing photos before uploading them to a website, blog, or online store.
Getting a set of attachments under an email provider's 25 MB limit.
Meeting a portal's strict per-file size cap — set the max-size slider to the cap and let the tool find the quality that fits.
Shrinking screenshots and phone photos before posting them to chat tools or ticketing systems that throttle large uploads.

Frequently asked questions

Tips

Set the max-size slider to your real constraint (e.g. 1 MB for a form upload) rather than guessing at quality percentages — the tool iterates to hit the target for you.
Compress copies, not originals: keep the full-quality file archived and publish the compressed one. Lossy compression can't be undone.

100% private — runs in your browser

Convertora processes everything on your device using JavaScript and WebAssembly. Files never leave your browser, are never uploaded to a server, and are never seen by us or anyone else. The moment you close the tab, the data is gone — there is no temporary cloud copy, no log entry, no retained backup.

Because the work happens locally, processing speed depends on your device — but there are no rate limits, no daily caps, and no file size restrictions beyond what your browser can handle in memory. No signup, no account, no payment. The tool works the same in incognito mode, on a corporate network, or after the page has loaded once, even with the network disconnected.