How it works
- Add your images and enter the target in KB (1 MB = 1,024 KB). Optionally set a maximum width and height.
- Click Compress. For each image the tool encodes at different qualities, keeping the highest one that fits. If none does, it shrinks the image by 15% and tries again.
- The result shows the final dimensions, quality and size, and whether it is under the target.
Size falls as quality falls, but not in a straight line, and every photo behaves differently: a photo of a sky compresses far more than one of gravel. That is why the tool measures rather than guesses. Each trial is a real encode, so the size you see is the size you get.
Why portals have KB limits
Government, exam and job portals were often built when bandwidth and storage were expensive, and many still check every upload against a fixed limit. Small files also load quickly for the assessor on any connection. The limits are often tight, 50, 100 or 200 KB, because the portal only needs a recognisable photo or a legible document, not a print-quality file.
Common limits
- 50 KB: exam applications and older government forms (photo and signature uploads).
- 100 KB: some visa and exam photo uploads.
- 200 KB: profile photos, ID uploads and online forms.
- 1 MB: email attachments and listing photos where speed matters.
- 2 MB: job portals and general uploads.
For passport and visa photos with exact pixel sizes as well as KB limits, use the photo maker, whose presets match each portal's dimensions; its KB tool is tuned for those. Platform presets here cover ImmiAccount, SEEK, LinkedIn, Etsy, eBay and Shopify.
Hitting a limit without ruining the photo
- Start from the original, not a copy that has already been compressed. Each lossy pass adds artefacts.
- Crop first. Background you do not need costs bytes; cropping a head-and-shoulders photo tightly can halve its size.
- Reduce dimensions sensibly. A 600 × 800 photo is plenty for most portal uploads; the search reduces size only as far as needed, but setting a maximum yourself avoids it trying huge sizes first.
- Use WebP or AVIF where accepted. At the same size they look noticeably better than JPEG.
- Check the result at 100%. Faces and text should be clean; if you see blocky skin or smeared letters, allow a few more KB or crop tighter.
Documents and scans
For scanned documents, legibility of the smallest text is what matters. Greyscale scans are much smaller than colour ones; if the portal accepts PDF, a compressed PDF may be better than a JPEG of each page.
Several images
Every image in the batch gets the same target. Each is searched separately, so a simple photo may end up at high quality and a detailed one at lower quality, both under the limit. Download all as a ZIP when done.
How long it takes
Each step in the search is a real encode, so a large photo takes a second or two, longer for AVIF and on phones. The search is capped so it never runs away: about eight quality steps at each size and at most a dozen size steps. Batches are processed one image at a time with a progress bar, and Cancel stops immediately.
Troubleshooting
- "Could not reach the target". The image would need to be tiny to fit. Crop it, or raise the limit if the portal allows.
- The portal still says the file is too big. Some forms count 1 KB as 1,000 bytes; set your target 3% lower.
- The portal rejects the format. Use JPEG; it is accepted almost everywhere.
Quality versus dimensions
Two things set a JPEG's size: how many pixels it has and how hard each block of pixels is compressed. Lowering quality keeps every pixel but blurs fine detail and adds blocky artefacts; reducing dimensions keeps each pixel crisp but shows less detail overall. For on-screen checks, which is what most portals do, a slightly smaller, clean image looks better than a full-size, heavily compressed one. That is why the search stops lowering quality at a floor and shrinks the image instead. If you would rather keep the dimensions and accept artefacts, set the maximum width and height to the original size and lower the highest quality to try.
Private by design
The image never leaves your device. It is decoded in your browser, processed in a background worker by open-source codecs compiled to WebAssembly (MozJPEG, libwebp, libavif and OxiPNG, via the jsquash project, plus pica for resizing) and handed back as a download. There is no upload, no account and no server copy to delete. You can confirm it in your browser's developer tools: the Network tab shows the page's own files and the codec files loading, and nothing carrying your image. After the first visit the tools work offline.