Compress a PDF to a specific size
Upload forms rarely ask for "a smaller PDF" — they ask for a file under a hard number: 100 KB for a government portal, 500 KB for a job application, 2 MB for an email attachment. This page maps those targets to the compression level that usually reaches them, and explains what to do when a target is out of reach.
Compression is not magic arithmetic. A PDF's size comes almost entirely from the images inside it, so what shrinks is scans and photos, not text.
Which level to use for each target
Start one level above what you think you need, then check the reported output size before downloading.
| Target size | Start with | Realistic for |
|---|---|---|
| Under 100 KB | Maximum | 1–3 page text documents, simple forms |
| Under 200 KB | Maximum | Short scanned documents, single photos |
| Under 500 KB | Medium | Most everyday scans and reports |
| Under 1 MB | Medium | Multi-page scans, image-heavy decks |
| Under 2 MB (email) | Small or Medium | Almost any ordinary document |
Why some PDFs will not reach a small target
A 40-page colour scan contains 40 photographs. Even aggressive re-encoding leaves a floor below which the pages become unreadable, and no tool can go under it while keeping the document usable.
If a portal demands 100 KB and your scan will not get there, the practical fixes are to scan in greyscale or black-and-white instead of colour, scan at 200 dpi rather than 600, or split the document and upload it in parts.
- Rescan in greyscale — often a 60–70% reduction on its own.
- Reduce scanner resolution to 200–300 dpi for text documents.
- Split the file and submit the required pages only.
- Remove pages that are not needed, then compress again.
Do not compress the same file twice
Each pass re-encodes images that have already lost detail, so a second round costs visible quality and returns very little size. If Medium was not enough, go back to your original file and run Maximum on it instead of compressing the compressed copy.
Step by step
- 1Open the Compress tool and add your PDF.
- 2Choose the level suggested for your target size above.
- 3Read the before-and-after size shown after processing.
- 4If you are still over, return to the original and try the next level up.
- 5Download the file once it is under your limit.
Frequently asked questions
- Can I compress a PDF to exactly 100 KB?
- No tool can guarantee an exact figure, because the outcome depends on what is inside the document. Maximum compression reaches 100 KB for short, mostly-text PDFs; heavy colour scans usually cannot.
- Is compressing to a target size free?
- Small and Medium compression are free. Maximum compression, which reaches the tightest targets, is included with Pro.
- Will text stay sharp?
- Yes. Text in a digitally generated PDF is stored as vectors and is not degraded by compression. Only embedded images are re-encoded.
- Why did my PDF barely shrink?
- It was probably already efficient — a text-only PDF has very little to remove. Big reductions come from image-heavy and scanned documents.
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