How to Compress an Image to 100 KB (or Any Exact Size)

"File must be less than 100 KB." If you've applied for an ID card, a visa, an exam, or a job through an online portal, you've met this error. Your phone takes 4 MB photos; the form wants 2% of that. Here's how to close the gap without ending up with a smeared mess.

The direct route: target a size

Most compressors make you guess at a quality slider and hope. The MB to kB tool works the other way around: you tell it the target — say 100 KB — and it searches for the highest quality that fits under it.

1. Open MB to kB and drop your image in.
2. Enter your target size (e.g. 100 KB).
3. Convert — the tool finds the best quality that fits the budget.
4. Download and upload to your portal. Done.

What actually shrinks an image

Image file size comes from three things, and you can trade on all of them:

A 4000×3000 photo displayed in a 600×450 slot on a form is storing 44× more pixels than anyone will ever see. Resizing first is often the single biggest win — do it with the Resize Image tool, then compress.

Quality tips for tiny targets

• Start from the original, not from an already-compressed copy. Every re-save of a JPG loses a little more.
• Crop away what you don't need with the Crop Image tool — fewer pixels spent on background means more quality budget for the subject.
• Prefer JPG or WebP for photos. PNG is lossless and will blow way past small size targets on photographic content (see our format comparison).
• Faces first. For ID-style photos, make the face large in the frame; compression artifacts are least visible on smooth, well-lit subjects.

For general shrinking (no exact target)

If you just want the file smaller and don't have a hard number to hit, the Compress Image tool does one-click reduction with sensible defaults.

Privacy

Photos are processed in memory and discarded when your download is served — relevant when the image you're compressing is a passport scan or an ID document. Nothing is stored, viewed, or indexed.

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Hit your target now: open MB to kB, type the number the portal demands, and get a file that fits on the first try.