How to Compress a PDF Under 1MB
Under 1MB is reachable for most ordinary scans. Pick the gentlest mode that gets there, and work out a per-page budget first so you know whether it's realistic.
Do the budget first
Divide the limit by the number of pages:
| Pages | Budget per page at 1 MB |
|---|---|
| 2 | about 500 KB |
| 10 | about 100 KB |
| 40 | about 25 KB |
A scanned page is a picture, so each page needs enough bytes to stay readable. If your budget per page is large, a gentle mode will do. If it is tiny, expect the tool to stop at its floor and report “target not reached”.
The modes
Compress PDF never redraws pages as pictures. It re-compresses the pictures inside the PDF and leaves text, vectors, fonts and page sizes alone.
| Mode | What it does | Good for |
|---|---|---|
| Balanced | Pictures up to 200 DPI; aims for roughly 30% smaller | The first thing to try |
| Smaller file | Pictures up to 150 DPI; aims for roughly 50% smaller | When Balanced isn’t enough |
| Target size | Searches for the best quality that reaches your number, down to a floor of 120 DPI and JPEG quality 50 | A hard limit |
| Custom | Your own quality and DPI, optionally grayscale | Fine control |
Balanced and Smaller are adaptive: they lower quality step by step until the goal is met, but stop early if a picture drops below a measured similarity guard against its source (95% for Balanced, 92% for Smaller). If a picture can’t shrink by at least 8% inside the guard, it is left alone, and the result says so.
Which mode got real PDFs under 1MB
From the real-file tests (sizes in KB, Safari’s engine):
| Kind of PDF | Original | Balanced | Smaller | Under 1 MB? |
|---|---|---|---|---|
| Scanned certificate | 1,110 | 681 | 302 | Balanced |
| Scanned document | 1,420 | 942 | 618 | Balanced |
| Scanned report with a text layer | 1,790 | 1,190 | 850 | Only Smaller |
| Scanned annual report | 2,530 | 2,190 | 2,150 | No |
| Scanned certificate, huge page | 18,830 | 5,820 | 2,780 | Only a 500 KB target (927) |
The pattern: moderate scans fit under 1 MB with Balanced; larger or denser ones need Smaller; and some need a target. A few don’t compress much at all.
Steps
- Try Balanced. Check the size and the “what was kept” report.
- If it’s still over, try Smaller, or set a Target size of 1 MB.
- Open the result and zoom in on text before you upload. See how to compress a PDF without blurry text.
If nothing gets there, read PDF too large to upload for the next options.