Compress Image Online

How to use the Compress Image

1. Drop one or more pictures on the box, click it to choose files, or paste a screenshot with Ctrl+V (⌘+V on a Mac).
2. Pick an output format. JPEG gives the smallest files for photos, WebP is smaller still, and “Keep the original format” leaves PNG screenshots as PNG.
3. Move the Quality slider. 75 is a safe place to start: lower it for email and web pages, raise it for pictures you may print.
4. For very large photos, type a Longest side such as 1600 px. Removing pixels saves far more than lowering quality alone.
5. Check the new size shown on each row, then download a single file or press “Download all (ZIP)”.

How image compression works

A JPEG stores a picture as small blocks of smooth colour change and quietly drops detail that the eye barely notices: tiny colour differences, fine noise, texture in shadows. The Quality slider decides how much of that detail is thrown away. At 90 and above the result is practically indistinguishable from the original; at 75 you will normally save half the file size or more with no visible change at normal viewing size; below 50 blocky patches start to appear around edges and on faces.

PNG works differently. It is lossless, so every pixel is kept exactly, which is why a PNG screenshot shrinks very little but a PNG photo is enormous. WebP is a newer format that can do both lossy and lossless coding and usually produces smaller files than JPEG at the same visual quality. If the place you are uploading to accepts WebP, it is the most efficient choice; if you are not sure, choose JPEG, which every website, app and printer understands.

Which quality should I choose?

These starting points work for most pictures. Compare the preview and the saving, then adjust.

Resize first, then compress

File size follows the number of pixels. A phone photo is typically 12 megapixels (4032 × 3024 px), yet even a 4K monitor is only 3840 px wide, and a page on a phone shows an image at 400–800 px. Halving the width and height keeps only a quarter of the pixels, so the file becomes roughly four times smaller before quality is even touched. Typing 1600 into “Longest side” gives most photos a good result on every screen, and you can lower the quality only slightly instead of heavily.

If you need a specific width and height rather than a maximum, use the Resize Image tool, and if you want to hit an exact number of kilobytes, use one of the size-target tools such as Compress Image to 50 KB.

When the result is not smaller

Some files have little left to remove. Pictures that were already saved by a messaging app or social network have been compressed once, and PNG screenshots with large flat areas are already efficient. When a recompressed copy would be bigger than the file you added, this tool keeps your original and tells you so rather than handing back something worse.

For PNG photos and screenshots the biggest saving comes from changing the format: choose JPEG or WebP above. Logos, line art and pictures with transparency should stay PNG, because JPEG has no transparency and creates fuzzy halos around hard edges.

Privacy and limits

The pictures are decoded and re-encoded by your own browser; no file is sent to a server, and no account or watermark is involved. The re-encoded copy also contains no camera or GPS metadata, a useful side effect if you are about to share a photo (the EXIF remover explains what is normally hidden in a photo).

There is no upload limit because nothing is uploaded. Extremely large pictures, roughly above 100 megapixels, may exceed what a browser can decode, and a very old phone will be slow with a long list of big files. In that case, process a few at a time.

Frequently asked questions