How to Compress a PDF to a Smaller File Size (Free & Online)

"File too large to attach." Every email provider caps attachments around 20–25 MB, and plenty of government and job portals cap uploads at 2 MB or less. Compressing the PDF is almost always the fix — and it takes seconds.

Compress a PDF in 3 steps

1. Open the free Compress PDF tool.
2. Drop in your PDF and pick a compression level.
3. Download the smaller file.

Which compression level should you choose?

• Recommended (ebook quality) — the sweet spot. Typically cuts file size by 40–70% while staying perfectly readable on screen and in print. Use this first.
• Extreme (smallest) — squeezes the file as hard as possible. Ideal when a portal demands something like "under 2 MB" and quality is secondary.
• Light (best quality) — gentle optimisation for documents that must stay print-perfect.

Why are PDFs so big in the first place?

Nine times out of ten: images. A PDF made from phone photos or high-resolution scans embeds every image at full size. Compression re-encodes those images at a resolution appropriate for reading, which is where the dramatic savings come from. Text-only PDFs are already small and won't shrink much — they don't need to.

Tips for the smallest possible PDF

• Scanning documents? Scan at 150 DPI instead of 600 — it reads just as well.
• Only need a few pages? Split the PDF first and compress just what you're sending.
• Sending many files? Merge them first, then compress once.

Your file is processed over HTTPS and deleted automatically after 24 hours — and if the compressor can't make your file smaller, it returns the original rather than a "compressed" file that grew.