How to reduce a PDF's file size without losing quality
An oversized PDF is a very concrete problem: the mailbox that rejects attachments beyond 10 or 25 MB, the government portal that caps uploads at 2 MB, the application platform that refuses your file. The good news is that much of a PDF's weight is often unnecessary — redundant internal structure, editing history, metadata, oversized images — and can be removed without degrading the document at all.
This guide walks through the techniques that actually work, from the simplest to the most advanced: lossless structural compression, removing unneeded pages and metadata, and optimizing images at the source. For each method we say what you can realistically expect: there is no point hoping to shrink an already-optimized PDF tenfold, but a scanned or heavily edited document can lose 30% of its weight in seconds.
Everything described here is free and happens directly in your browser: unlike most online compressors, your file is never uploaded to a server. That matters enormously the moment a document contains personal, banking or business information.
Why is your PDF so heavy?
A PDF's weight rarely comes from text, which weighs almost nothing. The real culprits are images (inserted photos, pages scanned at high resolution), fonts embedded several times over, and above all the file's internal structure: every successive edit in a PDF editor adds objects without removing the old ones. A PDF that has passed through several hands accumulates duplicates, editing history and stale cross-reference tables. Identifying the cause helps you pick the right method: a 20 MB scan is treated differently from a 5 MB report exported from Word.
Lossless compression: the first thing to try
Always start with lossless optimization: it rewrites the file's structure (compressed xref table, compacted object streams, merged duplicates) without touching images or fonts. The visual rendering stays strictly identical — zero risk for an official document. On a typical PDF, expect savings of 5 to 30%; on a file edited many times, it can be more. Our Compress tool applies this treatment in seconds, directly in your browser, with no file size limit and without ever sending the document online.
Remove unneeded pages and metadata
Every page costs weight: if your 40-page bundle only needs 12, extracting just the useful pages is the most effective reduction there is. The Delete / Extract tool accepts ranges like “1-3, 7, 12-15” and produces a clean new PDF. Think about metadata too: title, author, subject, keywords and traces of the originating software. Removing them only saves a few kilobytes, but it brings a double benefit: a lighter file and an anonymised document — which matters before any public distribution.
Slim down images before the PDF is even created
If the PDF hasn't been created yet, act at the source: that is where the biggest savings live. A smartphone photo weighs 3 to 8 MB; resized to 1,500 pixels wide and saved as JPEG at quality 80, it drops below 500 KB with no visible difference on screen or in office printing. To digitise paper documents, the Scan to PDF tool applies a “document” filter (grayscale or black & white) that drastically reduces weight compared with a raw colour photo. Then assemble your optimized images with Image to PDF.
Hitting a target size: email, applications, government portals
When a precise limit is imposed — 2 MB for a portal, 10 MB for a mailbox — proceed in stages: lossless optimization first, then removal of pages that aren't required, then, if needed, splitting the document. The Split tool lets you send a bundle as two “part 1 / part 2” files that any mailbox accepts. This step-by-step approach preserves maximum quality at every stage, rather than crushing the whole document with aggressive compression that would make supporting documents unreadable.
Compressing without uploading: why it matters
Most online compressors upload your document to their servers, process it, and promise to delete it “after a few hours”. For a contract, an ID document, a bank statement or a medical file, that promise rests entirely on trust. Our tool works differently: compression runs as WebAssembly inside your browser, the file never leaves your device, and the app even works offline. You can verify it yourself: switch off your Wi-Fi after the page loads — compression still works.