Image KB Resizer
Resize images to your target KB size precisely. Set exact file size for ID photos, passports, and uploads. Batch processing, free.
About This Tool
Image KB Resizer shrinks your image to a specific target file size in kilobytes. Simply enter the desired KB limit β the tool automatically adjusts quality and dimensions to hit that target. Perfect for passport photos, online applications, forum avatars, and any upload form with a strict size cap.
π‘ Use this when you need exact file sizes β ID photos (200KB), passport photos (500KB), application uploads, and more.
Drag & drop images or click to upload
JPG, PNG, WebP Β· Up to 20 files
How to Use
- Upload images by dragging or clicking the upload area (up to 20 files).
- Set your target size (KB) using preset buttons or manual input.
- Optionally set max resolution limit and output format.
- Click Convert β quality and resolution are adjusted automatically.
- Review results and download individually or as a ZIP.
Why Specify Exact KB Size?
Many job applications, government portals, and exam registrations require photos under a specific file size. Regular image compressors only adjust quality, making it hard to hit exact KB targets.
Common file size requirements
- ID photos (civil service exams): under 200KB
- Passport photos: under 500KB
- Driver's license photos: under 100KB
- Online applications: typically 200~500KB
- Resume attachments: 100~300KB
Tips for Reducing Image Size
- JPG is the most effective format for reducing photo file sizes.
- WebP produces files 25-35% smaller than JPG at equivalent quality.
- Reducing resolution significantly decreases file size β ID photos usually need only 300-400px.
- PNG is lossless and inefficient for photos. It's best for icons and text images.
Frequently Asked Questions
Can it hit the exact target KB?
Our binary search algorithm adjusts JPEG/WebP quality to get as close to your target KB as possible. If quality alone isn't enough, resolution is also reduced automatically.
How do I resize an ID photo to 200KB?
Upload your photo, enter 200 in the target size field or click the 200KB preset button. Choose JPG as the output format for the best results.
Can I process multiple files at once?
Yes, you can upload and process up to 20 files simultaneously. After processing, download individually or as a ZIP archive.
Are my photos uploaded to a server?
No. All processing uses the Canvas API and happens 100% in your browser. Your photos never leave your device.
Can I reduce file size with PNG format?
PNG is lossless and doesn't support quality-based compression. We recommend choosing JPG or WebP format for effective size reduction.
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How It Works
The tool uses an iterative binary-search algorithm on the HTML5 Canvas API's toBlob() quality parameter to converge on your target file size. It starts by encoding the image at medium quality, checks the resulting blob size, and adjusts the quality up or down accordingly. If quality reduction alone isn't sufficient, the image dimensions are also scaled down proportionally. The loop typically converges within 5β8 iterations, delivering a result that is at or just below the specified KB limit.
Every step β decoding, resizing, and re-encoding β runs entirely in your browser via the Canvas API. No image data is ever sent to a server, guaranteeing full privacy.