How to Reduce PDF File Size: What Actually Works
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Why PDFs get large, which compression methods help for scans, photos and text documents, and how to avoid ruining quality.
Email attachments are often capped at 20–25 MB, and many upload forms accept even less. Here is what makes PDFs large and how to shrink them without making them unreadable.
Why some PDFs are so big
- Images. Scans and photos are by far the largest part of most heavy PDFs. A single phone photo can be 3–5 MB.
- Embedded fonts. Full font files can add hundreds of kilobytes, though most tools embed only the characters used.
- Leftover data. Editing a PDF repeatedly can leave old, unused objects, thumbnails and metadata inside the file.
Pick the right method
| Your PDF | What helps | Expected result |
|---|---|---|
| Mostly text (exported from Word, a bank statement) | Lossless cleanup | Often small savings — the file may already be optimal |
| Photos or illustrations | Recompress images at moderate quality, limit resolution | Frequently 40–80% smaller |
| Scanned pages | Recompress, or rasterize pages to JPEG | Large savings, but text is an image either way |
These ranges are typical, not guaranteed — results depend entirely on the file. A good tool shows you the real size before and after rather than promising a percentage.
Using Compress PDF
- Open Compress PDF and choose your file.
- Start with Balanced: JPEG images are recompressed at quality 72 and limited to 2000 px on their long side; text and vector graphics are untouched.
- If that isn’t enough, try Strong, which also converts large lossless images to JPEG.
- As a last resort, Maximum (rasterize) turns each page into an image. It is very effective on scans but removes selectable text, links and form fields.
When compression won’t help
If a PDF is mostly text and vectors, there is little to remove. The tool will tell you when the result isn’t meaningfully smaller — keep your original in that case. Splitting a long document into parts with Split PDF is another way to get under an upload limit.
Protect quality
- Never compress the only copy of a document; the tool always creates a new file.
- Zoom into photos and small print in the result before sending it.
- Avoid compressing the same file repeatedly — each lossy pass degrades images further.
