Which PDF compression mode should I choose?
Try structural compression first when you need to retain selectable text. Choose scanned-PDF mode only if an image-only copy is acceptable: it renders pages as images and does not preserve searchable text. Compare the output size and readability with the original before sending it.
Important limit: An already optimized PDF may not get smaller. No preset guarantees a target such as 200 KB; reducing resolution can make small text less readable.
Choose PDF compression settings · Processing evidence and privacy scope
Written and maintained by Fahad Farid · Updated October 9, 2026
Choose the mode that fits your document
| Mode | Best starting point | Trade-off |
|---|---|---|
| Structural optimization | PDFs with selectable text or interactive content | Rewrites PDF structure without rasterizing pages. Embedded images are not downsampled; savings may be small or zero. |
| Scanned / image-only compression | Large scanned pages or photo-heavy documents where a visual copy is acceptable | Rebuilds every page as a JPEG image. Searchable text, links, forms, bookmarks, attachments and accessibility structure are not retained. |
Try a sample before using an important document
Download the scanned-page practice PDF. It contains fictional text as a high-resolution image. Open Compress PDF, select the sample, choose scanned mode and start with Balanced. Confirm that image-only output is acceptable, then compress.
Sample compression results
The included scan sample was 1,472.9 KB. A local engine test on September 24, 2026 produced the results below. These figures describe this synthetic sample, not typical or guaranteed savings; a browser JPEG encoder may produce different sizes.
| Preset | Output | Reduction |
|---|---|---|
| Small | 68.3 KB | 95.4% |
| Balanced | 121.2 KB | 91.8% |
| Clear | 257.2 KB | 82.5% |
- Read the original size, result size and percentage saved.
- Download the result and zoom into the numbered lines.
- If small text is hard to read, try Clearer text using the original file.
- If the portal still rejects the size, try Smaller file or remove unnecessary pages. No preset guarantees a particular upload limit.
What the three scan presets change
Smaller file targets 96 DPI with JPEG quality 55%; Balanced targets 120 DPI at 72%; Clearer text targets 150 DPI at 85%. These are encoding settings, not a percentage of original quality or a promised size reduction. Very large pages are capped at five million rendered pixels to reduce browser memory use.
When compression does not help
An already-optimized PDF can become larger when rewritten. ToolVero compares sizes and retains the unchanged original if the attempted output is not smaller. The result message reports the attempted size so you can see what happened. Removing an unnecessary page using Delete PDF Pages can help more than repeated compression.
Limits and document integrity
Inputs are limited to 80 MB. Scanned mode supports up to 150 pages in a run and processes pages sequentially. A low-memory phone can still fail on a complex file below those limits. Cancel stops after the current processing step; it may not be immediate while a page is rendering. Password-protected PDFs must first be unlocked using the correct password.
PDFs with detected signature dictionaries or signature fields are rejected because rewriting would change the signed document. Structural mode avoids intentionally rasterizing text, but you should still check unusual forms, annotations and document features. Keep the original.
Privacy
PDF processing runs locally in your browser. The compressor's PDF libraries and worker are served by ToolVero rather than an external CDN. A website request or an advertising request is separate from uploading your selected document. Read the Privacy Center for the wider site policy.
Frequently asked questions
Can I compress a PDF to exactly 200 KB?
No exact output size is guaranteed. The page content, resolution and quality setting determine the result. Compare the result with the actual limit before submission.
Will scanned mode preserve searchable text?
No. It creates image-only pages and does not add an OCR text layer.
Does structural mode recompress photographs?
No. It rewrites the document structure without downsampling the embedded images. Use scanned mode only if its trade-offs are acceptable.
Choose a file-size target without losing necessary content
Start with the recipient’s actual upload limit and required features. A file that meets the size limit but loses searchable text or readable labels is not a successful result. Keep the original and compare every new attempt with it, rather than recompressing an already degraded copy.
- Read the current file size and the destination limit. Leave some margin if the destination reports units differently.
- Remove unnecessary pages with Delete PDF Pages, if the recipient permits this.
- Use Compress PDF in structural mode first for text-based documents.
- Use image-only mode only when its loss of text selection, links and interactive features is acceptable.
- Open the output at normal reading size and zoom into the smallest important text. Check stamps, charts and thin lines too.
Example decision: a scanned application
If the receiving portal only needs a readable visual copy, a scan preset may be suitable. If it needs fillable fields, accessible text or a verifiable digital signature, an image-only reconstruction is the wrong tradeoff. Ask which requirements matter before lowering image quality.
What to do when the target is unreachable
Do not keep reducing quality until the document is unreadable. Ask whether separate attachments or a different delivery method are accepted. Splitting with Split PDF helps only when several files are allowed. For limits and size planning, read the PDF file-size guide and follow prepare a PDF for submission.