Image Optimizer

What Image Optimizer does

Image Optimizer is about file size: it saves an image again in its own format at the quality you choose, keeping the exact width and height. For a different format use Image Converter, for new dimensions use Image Resizer, and for a color cast use Image Color Changer.

Unlike the converter, it never asks for an output type. A JPG comes back as a JPG and a WEBP as a WEBP, so the smaller copy can stand in for the original anywhere that expects that type. The savings come from the Quality slider, which applies to JPG and WEBP output.

How to use it

1. Use Choose File to open the image you want smaller. Its dimensions and current file size appear next to the buttons.
2. Move the Quality slider. A new copy is encoded shortly after each move.
3. Compare the size under Output Preview with the original size at the top, and look over the preview for smearing or blocky edges.
4. When the balance looks right, select Download. If the output is larger than the original, keep the original instead.

Formats and limits

• Input: PNG, JPG, JPEG, WEBP, and BMP.
• Output keeps the type of PNG, JPG, and WEBP files, including a .jpeg extension if you used one. BMP files are saved as PNG.
• Names gain -optimized, for example logo-optimized.png.
• Width and height are never changed. Metadata such as camera EXIF data is dropped when the image is redrawn, which trims a few bytes on its own.

Settings explained

Quality

From 1% to 100%, starting at 80%. It sets the compression level for JPG and WEBP output. Photos often look unchanged between 70% and 85%; thumbnails can go lower. PNG is lossless, so the slider does nothing for PNG output.

Further reading

• When a file is too large for a browser tool - Compare compressed file size with decoded memory and choose a practical workflow for large images and videos.
• PNG, JPG, or WebP - Compare image formats, preserve transparency, and inspect quality and size before saving.

Privacy

Compression happens in this browser tab using its built-in image encoder. The picture is not uploaded or stored anywhere else, and the optimized copy stays in memory until you download it or leave the page.

FAQ

Why did my PNG not shrink, or even grow?

PNG output ignores the slider, so the tool can only re-save the same pixels with your browser's PNG encoder. That may land a little above or below the original. For a real cut, turn the PNG into WebP or JPG with Image Converter.

Why is my optimized JPG larger than the original?

The original was likely saved at a lower quality than the slider setting. Encoding at a higher number adds bytes without adding detail, so lower Quality until the output drops below the original.

Should I optimize a file more than once?

Avoid it. Every pass throws away more detail while saving less each time. Start again from the untouched original instead.

Can it reduce the pixel dimensions too?

No, the size in pixels stays fixed. Scaling a large photo down to the size it is displayed at often saves far more, so try Image Resizer first and optimize the result.

Related tools

• Image Resizer - cut pixel dimensions before compressing.
• Image Converter - move to a more compact format such as WebP.
• Image Compare - check the compressed result against the original.
• EXIF Viewer and Remover - strip location and camera data as well.
• GIF Optimizer - shrink animated GIFs, which this tool does not accept.