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5 ways to reduce PDF file size without ruining quality
A smaller PDF is easier to email and upload, but “make it smaller” is not one operation. A scanned application form, a report exported from Word and a portfolio full of photographs become large for different reasons. Start by identifying what is inside the file, then use the least destructive change that solves the actual problem.
1. Remove pages you do not need
The cleanest byte is the one the document no longer needs. Blank scanner pages, duplicate attachments, old signature pages and accidental photos can add several megabytes without helping the recipient. Split the PDF or rebuild it with only the required pages before changing image quality.
Check the submission instructions first. A blank back page may be intentional, and removing a terms page from a signed form can make the document incomplete.
2. Compress photographs more than text
Photos tolerate JPEG compression because small colour changes are hard to notice. Screenshots, diagrams and text do not: heavy JPEG compression produces fuzzy edges and blocks around letters. Use a balanced preset for mixed documents and a stronger setting only when the pages are mostly camera images.
Judge the result at the size someone will actually read it. Zooming to 800% exposes artifacts that will never appear on a phone, while checking only a thumbnail can hide an unreadable account number.
3. Use a sensible image resolution
A phone can capture far more pixels than an A4 page needs. For screen reading, roughly 120–150 pixels per inch is often enough. Printed forms and small type benefit from about 200–300 ppi. Going far beyond that increases file size quickly without adding visible detail to an ordinary office document.
Resolution cannot repair a blurred source. Keep the sharp original and reduce a copy; repeatedly compressing an already compressed file compounds the damage.
4. Keep real text as text
A Word document exported properly to PDF stores letters and fonts efficiently. Printing every page to an image usually makes the file larger and removes search, copy and accessibility. If text is already selectable, prefer a compressor that preserves that structure.
Scans are different because each page is already a picture. OCR can add searchable text, but it does not automatically remove the underlying page image.
5. Compare the result, not only the percentage
Open the compressed file and inspect signatures, QR codes, stamps, tables and the smallest text. Confirm the page count and try any links. A 90% reduction is not a success if the receiving office cannot read the document.
Keep the original until the upload is accepted. If the result is still too large, remove unnecessary pages first, then step down one quality level at a time instead of jumping immediately to the strongest compression.