An upload limit should not cost you missing words or unreadable pages. Start with a copy of the original and check the recipient’s maximum size. This guide uses decimal units: 1 KB is 1,000 bytes and 1 MB is 1,000,000 bytes. Portals may use different units or apply their limits to an entire batch.
Step one: set your size target
Open Compress PDF, choose one PDF and enter a limit such as 2 MB or 500 KB. Leave the field blank if you only want safe compression without a particular ceiling. The original stays on your device.
What safe compression changes
The compressor rewrites the storage structure using compressed object containers and checks original document objects and streams against the reopened result. It may also compact supported embedded TrueType fonts while preserving every glyph ID, outline and spacing. That stronger pass requires an all-page rendered-pixel and text-position comparison. It does not reduce image quality, flatten forms, remove attachments or strip metadata.
Extractable text and a correct page count alone cannot prove that a PDF still looks right: damaged font data can leave text selectable while letters disappear. Filozy does not renumber glyphs or rewrite page text. Font optimization is skipped for interactive forms, unsupported fonts, documents over 80 pages, oversized rendering surfaces, or browsers without the required local renderer. It also falls back if any verification fails. Always check the downloaded copy in your usual viewer.
Step two: read the actual result
- Target met: the result is at or below your chosen byte limit.
- Target not reached: the safest available output is still larger than the limit. Its content was not sacrificed to force the size.
- Original preserved: repacking did not save space, a preservation check failed, or the document requires protection from rewriting. The downloaded bytes are unchanged.
The selected level still attempts compression even when the original already meets your optional target. Maximum uses the broadest supported font optimization; Balanced checks larger fonts in documents of up to 20 pages; Minimal only repacks the structure. All levels preserve content and image quality. Signed documents, signature fields and XFA forms are returned unchanged because a rewrite may invalidate their integrity. Password-protected PDFs require an authorized unlocked copy.
Step three: review before sending
Open the result in your usual PDF viewer. Compare every page, including small print, tables, symbols, signatures and any form fields. Check the exact reported size rather than relying on a rounded filename or a promised percentage. Keep the original until the recipient accepts the file.
If the file is still too large
Ask whether the recipient allows multiple parts. Advanced Split can separate a document, but splitting is a different operation and may not suit signed documents or interactive forms. Review its restrictions before proceeding.
If a final, non-editable form is specifically required, Flatten PDF is a separate, deliberate choice. Flattening changes interactivity and is not part of preservation-first compression; it is not guaranteed to save space.
You can also return to the source document and export a smaller copy. Lower image resolution can reduce size, but changes quality and may damage small text in scans. Filozy’s preservation-first compressor does not make that decision for you. Never repeatedly compress a damaged result in an attempt to recover missing content; return to the original.