Free image compressor

What does an image compressor do?

An image compressor makes image files smaller so pages load faster, emails stay under attachment limits and uploads go through. It does that in two ways: by re-encoding the image with a more efficient format or a lower quality setting, and by reducing its pixel size. For screenshots and photos on the web, the right combination often cuts the file a lot with no visible difference.

This tool decodes, resizes and re-encodes each image with your browser’s own image engine, so your files are never uploaded.

Which format should you choose?

AVIF appears only when your browser can encode it. If you don’t see it, use WebP.

How to compress a PNG

PNG is lossless, so its quality setting does nothing: the file stays a pixel-perfect copy. To compress a PNG you have two real options. Convert it to WebP, which keeps transparency and usually makes screenshots much smaller, or reduce its width if it is bigger than it will ever be shown. Keep PNG only when the file must be lossless or the place you upload it to doesn’t accept WebP.

Quality and size: a short example

Say you have a full-screen screenshot from a high-resolution laptop display for a help article. The article column is about 800 pixels wide, so the extra pixels are never seen. Set a maximum width of about 1600 pixels (enough for sharp display on high-density screens), choose WebP and a quality around the middle of the scale. Then compare the preview with the original at 100% zoom. If small text looks soft, raise the quality a step; if it looks the same, try one step lower.

Best practices

Resize before you compress

Pixel size has the largest effect on file size. An image twice as wide as it is shown carries about four times the pixels it needs. Set a maximum width first, then tune quality.

Use higher quality for text

Photos hide compression well; screenshots with small text do not. For interface screenshots, stay at a higher quality or use PNG or WebP.

Keep your originals

Compression throws information away. Keep the original file so you can export a different size or format later without compressing an already compressed image.

Things to know

• Metadata is removed. Re-encoding in the browser drops EXIF data such as camera details and GPS location, and color profiles. That is good for privacy, but colors in wide-gamut photos can shift slightly.
• JPG has no transparency. Transparent areas become white when you convert to JPG.
• Images are never enlarged. A maximum size only scales larger images down.
• Bigger is possible. Converting an already well-compressed JPG to PNG, or raising the quality, can make a file larger. The tool shows the saving per image so you can spot it.

Which quality setting should you use?

There is no single right number, because quality settings are not comparable between formats and every image compresses differently. Use the before-and-after comparison instead of guessing. Start in the middle of the scale, look closely at the parts that show damage first, such as small text, thin lines and smooth gradients, and move the setting down until you notice a difference, then go one step back up. Photos usually tolerate lower settings than screenshots. Once you find a level that works for a type of image, reuse it for the whole batch so your pages look consistent.