How to compress a PDF without losing quality

What "without losing quality" really means

Need the file under a specific size, such as an email limit? See how to reduce PDF file size for four practical methods.

Every way of making a file smaller throws some information away. The goal is to discard only what you won't notice. For most people that means pages that still look sharp on screen and print cleanly, while the file becomes small enough to email or upload.

Where the savings come from depends on what's inside the PDF. In scans and photo-heavy documents, nearly all of the size is in the images, so there is a lot to save. A PDF that is mostly typed text is usually small already and has little to gain.

How Convertora compresses a PDF

Compress PDF re-renders each page as an image at the resolution and quality you choose, then rebuilds the PDF from those images. This gives reliable, predictable savings, especially on scans.

The trade-off: the text becomes part of the page image, so it can no longer be selected, copied or searched. If you need that, keep the original file, or use the compressed copy only for sending.

Settings that keep pages sharp

1. 1Open Compress PDF and add your file (up to 100 MB).
2. 2For the best-looking result, choose 300 DPI and Maximum quality. This is the setting to use for documents that will be printed or read closely.
3. 3For on-screen reading, 150 DPI with High quality is usually indistinguishable on a phone or laptop and noticeably smaller.
4. 4Compress, then compare the new size with the original. Both sizes are shown side by side.
5. 5Open the result and zoom into the smallest text. If it looks soft, go back and raise the DPI.

Which PDFs shrink well, and which don't

Shrink well: scanned paperwork, phone photos saved as PDF, image-heavy brochures and portfolios.

Shrink little or may grow: short, text-only PDFs exported from a word processor. Rendering them as images at a high DPI can produce a file as large as the original, or larger. Because the result size is always shown, you can simply keep the original if it isn't worth it.

Other ways to get a smaller file

Remove what you don't need. If only a few pages matter, Split PDF can pull out a range such as 3-8 as a new document without changing its quality.

Fix the source. If you're building a PDF from photos, shrink the photos first with Compress Image (it keeps the same format and dimensions), then combine them with JPG to PDF.

Privacy

Compression runs entirely in your browser. The PDF never leaves your device, which is useful for contracts, payslips and medical letters.

A quick check before you send it

Open the compressed file on the device the recipient is likely to use, often a phone, and read a paragraph of the smallest text at normal zoom. Check any signatures, stamps and photos too. If everything is clear, you're done. If not, raise the DPI one step and compress again. It only takes a few seconds, and it's better than having a form rejected because a scan is unreadable.

Frequently asked questions