How to Compress PDF to 100KB Online Free (Step-by-Step Guide)

1. Why 100KB File Limits Exist

Many online application portals—such as government employment forms (UPSC, SSC, IBPS), passport applications, and university admissions systems—enforce strict 100KB or 200KB file upload limits to save server storage and bandwidth.

Attempting to upload a 2MB scanned PDF result in generic portal error messages like "File size exceeds maximum allowed limit of 100 KB".

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2. 3-Step Strategy to Hit 100KB Target

Step 1: Compress Scanned Photos First

If your PDF consists of scanned certificates or marksheets, the high image resolution is responsible for 95% of the file weight.

1. Use Image Compressor to resize the scanned photo.
2. Set quality target to 70–75%.

Step 2: Convert Compressed Images to PDF

1. Open Image to PDF.
2. Select Standard A4 page layout.
3. Export your clean, lightweight PDF.

Step 3: Verify Output File Size

Check the output file properties to ensure it is under 100KB (typically 40KB–85KB after compression) before submitting to your portal.