Classic Converter
Classic Converter guides
Make a PDF smaller without losing what matters
The right way to reduce a PDF depends on what is inside it. A form needs its fields and text. A scanned receipt may mainly contain large images. Classic Converter offers two modes so you can make that tradeoff explicitly.
Start with preservation
Choose Preserve text & forms first. This rewrites the PDF while retaining selectable text, vectors, interactive form fields, and page sizes. A PDF that is already optimized may stay the same size or become larger. Keep whichever copy best meets your needs.
Use image output for scans
Shrink scans (images) renders pages as JPEG images and keeps their original physical page size. This can help with image-heavy scans, but it removes selectable text, interactive forms, links, and password protection from the output. It does not preserve a digital signature.
| Your document | Start with | What to check |
|---|---|---|
| Fillable form | Preserve text & forms | Fields still work and entries are retained |
| Text report | Preserve text & forms | Text is selectable and pages are complete |
| Scanned receipt | Preserve first, then image mode if needed | Small print, dates, and totals remain readable |
- Open PDF compression and select your original PDF.
- Try the default preservation mode and compare the resulting size.
- If it is still too large and you can accept the losses, choose image mode.
- Start with the provided quality and resolution settings. Reduce them gradually rather than immediately choosing the smallest output.
- Download and inspect every important page before replacing or sharing the file.
A practical example
For a scanned invoice attached to an email, try a moderate image quality and check the amount, tax number, and payment details at normal viewing size. A very small file is not useful if a digit becomes ambiguous. For an editable tax form, keep preservation mode so the recipient can still fill its fields.
Privacy and limits
Before compressing, you can extract only the pages you need or correct sideways pages. To combine two source documents, use Merge PDF and then check whether the combined file needs compression.
If you need an image for a slide or an upload form instead of a smaller PDF, use the PDF to JPG or PNG converter. It exports a separate image for each page.
Both compression modes run in your browser. The PDF is not uploaded to the conversion API for compression. Processing large image pages can use significant device memory. Keep the tab open and keep an untouched original.
Some encrypted files must be decrypted before an operation can export them. The separate decryption tool uses the server and requires the necessary password. Only remove protection from files you own or have permission to modify.
Can you guarantee a particular final file size?
No. The result depends on the original document and your settings. Image-heavy files and already optimized files respond differently.
Should I compress a digitally signed PDF?
Keep the signed original. Rewriting or rendering a PDF can invalidate or remove its signature. Share the original whenever preserving verifiable signatures matters.
Written for Classic Converter · Updated 20 September 2026