100% Free In-browser Custom KB target

Compress Image to Custom KB Size

Set any target file size from 10KB to 999KB. Perfect for form uploads, email attachments, and platforms with strict file size limits. No upload required.

Drop images here or click to browse

JPG, PNG, WebP • Batch compression supported

Accepts: any image
Output: .JPG
KB
Output is always JPG for smallest file size
Never uploaded·How to use this tool
0 files
Related tools: Resize to 20KB Compress Image Resize Image PNG to JPG

How it works

Compress to your target KB in 3 steps

1

Upload images

Select your images — JPG, PNG, WebP, or any common format.

2

Set target KB

Drag the slider or type your target file size in KB (10–999 KB).

3

Download compressed

Images are compressed to fit your target. Download individually or as ZIP.

FAQ

Frequently asked questions

The compressor iterates through quality levels (0.9 down to 0.05) and finds the highest quality that keeps the file under your target. The result is always at or below the target — it may be slightly smaller than the exact target (e.g. targeting 100KB might give 95KB).

Always JPG. JPEG compression provides the most control over file size for photographs. For very small targets, the output will be visibly degraded — JPG is simply the most efficient format for hitting specific byte sizes.

If the image converted to JPG at 90% quality is already below your target, it will be saved at high quality without unnecessary compression. The output is always the best quality that fits within your target.

No. All compression is done in your browser using the Canvas API. Your images never leave your device.

This tool supports up to 999KB (just under 1MB). For targets above 1MB, use our Compress Image tool which works in megabytes and can handle any target size.

Common targets: 20KB (passport/ID photos), 50KB (many government forms), 100KB (email attachments, profile photos), 200KB (social media uploads), 500KB (blog images). Use our dedicated "Resize to 20KB" tool if you specifically need 20KB.

Everything you need to know about MB to KB

Converting large images online has never been easier. JustDownSize processes everything locally in your browser using modern Web APIs — your files never leave your device, so your privacy is always protected.

Why use JustDownSize for mb to kb?

Unlike server-based tools that upload your files to remote servers, our tool runs entirely client-side. This means instant processing with no waiting in queues, no file size limits imposed by server constraints, and complete privacy — what you convert stays on your device.

Frequently asked questions about mb to kb

Our FAQ section above answers the most common questions. If you have additional questions, feel free to contact our support team.