Image Compressor

How do I use it?

Drag one or more JPG, PNG, WEBP, AVIF, or BMP files onto the canvas, or press Add images. Once the preview appears, turn on Target size in the settings below and type the number you need. The unit can be KB or MB.

Press Compress and every file is re-saved until it fits under the target, with the final size and dimensions shown in the result row. Download individual files from the list below, or use ALL ZIP to grab everything at once.

• Turn the target off to go back to the manual quality slider.
• Enable Resize as well and the target is met against the dimensions you set.
• With the target on, the quality slider is disabled because the tool computes that value.

What does target size mode actually do?

Instead of applying one quality value, it starts at 95%, measures the output, and lowers the value whenever the result is still too large, repeating up to eight times. Each pass halves the remaining range, so it converges on the highest quality that still fits under your target.

Give a 1.8MB photo a 200KB target and it usually lands in the 190KB range at around 40% quality. The result list writes out the values it used, such as Target 200 KB and Quality 41% · Scale 100%, so if the image looks too soft you can raise the target and run it again.

What happens when the target is out of reach?

Some files stay above the target even at the lowest quality, either because the original is very large or because the target is unrealistic. Rather than giving up, the tool steps the dimensions down and repeats the same search.

• The scale steps are 85%, 72%, 60%, 50%, 40%, 32%, 25%, 20%, and 15%.
• It stops at the largest step that satisfies the target, so nothing shrinks more than necessary.
• If it still cannot fit, that row gets a Target missed badge and you can download the smallest result it managed to produce.

A missed target is a signal that the number is unrealistic. Raising the target one step or switching the output to JPG costs less image quality than forcing it.

Target sizes people actually use

If you are not sure what number to type, these ranges cover most cases. The preset buttons fill them in directly.

• 50KB — forum avatars, small thumbnails, list icons.
• 100KB — inline blog images, email signatures.
• 200KB — product detail photos, homework and document attachments. The most common value.
• 500KB — hero images and banners where quality matters.
• 1MB — photos meant to be viewed enlarged, though not for print.

If the site you are uploading to states an exact limit, use that number. The tool packs as close to the ceiling as it can without crossing it, so a 200KB limit typically ends up around 199KB.

Choosing an output format

JPG or WEBP output works well for photos. AVIF and BMP can be uploaded, but the saved format is chosen from JPG, PNG, and WEBP. For logos, icons, and screenshots that need transparency or crisp edges, check PNG or WEBP first.

• JPG flattens transparency onto white and is the easiest format for hitting a target size.
• WEBP tends to look better than JPG at the same file size, which suits web publishing.
• PNG ignores the quality value in browsers, so reaching a target depends entirely on shrinking the dimensions.

One target across many images

With several files loaded you still set only one target. Each file is searched separately, so originals of very different sizes all end up under the same ceiling.

Load a 3MB photo alongside a 400KB photo with a 200KB target and the first loses a lot of quality while the second passes almost untouched. Because the same quality value is never forced onto both, the smaller file is not degraded for no reason.

When it finishes, use ALL ZIP in the result row for everything, or download only the files you need from the list below.

Check before compressing

A file that is already optimised for the web can grow when it is re-saved. If the original is a small icon or an already heavily compressed photo, read the result numbers before deciding to download.

When the resolution is far larger than it needs to be, use Resize to match the display size instead of crushing the quality. Taking a 4000px photo down to 1200px reaches the same target at a much higher quality.

Common mistakes

• Leaving the format on PNG — browser PNG saving ignores quality. Switch to JPG or WEBP when transparency is not needed.
• Not checking the unit — typing 200 while the unit still says MB sets a 200MB target and nothing changes.
• Picking an extreme target such as 10KB — you get a missed-target badge and an unreadable image.
• Recompressing an already compressed file — if the result is larger than the original, keep the original.
• Downloading without looking — below roughly 20% quality the damage is visible. Check the preview first.

How the browser processing works

The tool reads your selection with the File API and re-saves it with Canvas toBlob. The target search runs the same way, saving repeatedly inside the browser, so no file is sent to a Roberin server.

The trade-off is that encoding runs once per search step, so large images take a little longer. The 20MB limit and the output resolution ceiling exist to stay within browser memory.

Checklist before you download

• The final size in the result row is at or below the target.
• No row in the list is still carrying a Target missed badge.
• The quality percentage is not too low, and text and edges are still readable in the preview.
• No image that needs transparency was saved as JPG.
• For multiple files, you picked either ALL ZIP or the individual downloads.