Compress an Image Online Without Ruining It

To compress an image online, upload a JPG, PNG or WebP file, choose a quality level, and download the re-encoded result. The Image Compressor shows the exact size before and after, so you can see whether the run actually saved anything instead of trusting an estimate. It handles one image per run, up to 10 MB, and keeps the output in the same format as the input.

The important part is not the slider itself. It is knowing which files have room to shrink and which ones are already finished. A 4 MB photo from a phone usually compresses well. A 40 KB PNG logo often does not, and the tool will tell you so rather than pretending otherwise.

#What image compression actually does

Compressing an image means re-encoding it with fewer bits. For JPG and WebP, that is a lossy process: the encoder looks for detail a viewer is unlikely to notice and throws some of it away. A lower quality setting means more is discarded. For PNG, compression is lossless — the pixel data is repacked more efficiently, but nothing is removed.

That distinction explains most surprises. Lowering the JPG quality from 90 to 60 can cut a file in half. Lowering the PNG setting does not exist as a choice, because PNG has no equivalent dial: this tool always writes PNG at its maximum compression level.

There is also a difference between resizing and compressing. Compression keeps the same pixel dimensions and reduces the number of bytes per pixel. Resizing changes the dimensions. If a photo is 6000 pixels wide and only ever displayed at 1200, resizing does far more for the file size than any quality slider. This tool deliberately does one job: it compresses. For the other job, use the Bulk Image Resizer.

#How to compress an image online

1. Open the Image Compressor and choose a JPG, PNG or WebP file up to 10 MB.
2. Set the quality slider. It runs from 30 to 95 and starts at 70. Lower means a smaller file and more visible loss.
3. Press Run. The server re-encodes the image and measures both files on disk.
4. Read the result block. It lists the original size, the compressed size, the bytes saved and the percentage saved. If the output was larger, the result says so.
5. Download the processed file. The link is generated for that run and expires on the cleanup schedule, so save it somewhere permanent.

The uploaded original is not kept as a library of your images. The processed result is stored only long enough for you to download it, then removed by the temporary-file cleanup.

#Which quality setting should you use?

There is no single correct number, but these ranges are a sensible starting point:

For a page where the image is the product — a photographer's gallery, a product shot — start at 80 and compare. For a decorative banner, 60 is usually indistinguishable at its display size. The mistake is compressing everything to the lowest setting because the number looks impressive; a blurry hero image costs more in credibility than it saves in kilobytes.

PNG follows a different rule. Since the tool compresses PNG losslessly, the result is the smallest PNG it can produce without changing a pixel. If that is still too large, the file is probably a photograph saved as PNG, and converting it to JPG or WebP is the correct fix.

#Common problems and how to fix them

The file got bigger. This happens when the source was already compressed harder than the target setting, or when a PNG is re-encoded. Re-encoding an efficient file cannot invent savings. The result block reports a negative saving rather than hiding it. Keep the original in that case.

The image looks worse than expected. Lower quality amplifies existing artifacts. If the source was already a low-quality JPG, compressing it again compounds the damage. Start from the highest-quality original you have, not from a copy that has been through three chat apps.

The upload is rejected. The tool accepts JPG, PNG and WebP up to 10 MB. A HEIC file from an iPhone, a TIFF from a scanner, or a GIF animation will be rejected before processing. Convert the file to a supported format first.

Transparency disappeared. JPEG has no alpha channel, so a transparent image saved as JPG cannot keep its transparency. PNG and WebP can. This tool preserves the input format, so a transparent PNG stays a transparent PNG. If you convert a transparent PNG to JPG elsewhere, the transparent areas have to become a solid colour.

The saved percentage is small. That is often the honest answer. A well-exported WebP or an already-optimised JPG has little left to give. The useful move is to resize it to its display dimensions, not to push the quality lower.

#Tips that make a real difference

• Resize before you compress. A 4000-pixel image displayed at 800 pixels is wasting bytes no matter how low the quality goes.
• Keep the original. Compression is one-way. Store the source file and treat the compressed copy as a delivery asset.
• Do not re-compress repeatedly. Each lossy pass removes more detail. Go from the original to the final size in one step.
• Match the format to the content. Photographs suit JPG or WebP. Screenshots, logos and line art suit PNG, then WebP if the browser support fits your audience.
• Check at display size, not at 400%. Zooming in to inspect compression artifacts is not how anyone will view the image. Judge it in the layout where it appears.
• Compress the largest images first. One oversized hero image usually outweighs twenty small icons.

If you are preparing a whole folder, compressing files one at a time is slow. The bulk workflow is covered in the bulk image resizing guide, which runs in the browser and does not upload the pictures at all.

#Frequently asked questions

#Bottom line

Compression is a trade between bytes and detail, and the only trustworthy way to make that trade is to see both numbers. Upload the image, try a quality level, and compare the reported sizes before you commit. Start with the Image Compressor, and if the result is still too large, resize the image to the size it is actually displayed at before compressing it again.