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How to Compress a PDF for Online Uploads

A practical guide to reducing PDF file size for upload portals, tender submissions, email attachments, and business applications.

5 min read • Updated 2026-06-10

Many portals reject files that are too large. This happens often with scanned certificates, company documents, IDs, statements, and tender attachments. Compressing a PDF helps reduce the file size while keeping the document readable.

Why PDFs become too large

PDFs often become large when they include high-resolution scans, photos, colour pages, or many image-heavy pages. A document may look simple on screen but still contain large embedded images that make it hard to upload or email.

Compress before submission

Compressing before submission gives you time to check quality. Avoid waiting until the final upload deadline. If the portal has a strict size limit, compress and test the document early so you can still rescan or split the file if needed.

Balance size and readability

The smallest file is not always the best file. Tender documents, certificates, and bank letters must remain readable. After compression, zoom into names, numbers, signatures, stamps, and QR codes to confirm they still display clearly.

Quick checklist

  • Compress large scanned PDFs before upload
  • Check stamps, signatures, and QR codes after compression
  • Split a file if the portal still rejects it
  • Keep a high-quality original copy

Prepare your documents online

Use TenderPDF to process, organize, and prepare PDF documents for upload, sharing, and business workflows.