How to reduce PDF file size without ruining the quality

Email services cap attachments at around 20–25 MB, and many upload forms — job applications, visa portals, university systems — allow only a few megabytes. A PDF made from phone photos or a scanner easily goes over. The good news: most large PDFs can be made several times smaller without any visible difference.

Why PDFs get so big

• Photos and scans. Almost all of a large PDF’s size is usually images. A phone photo can be 3–5 MB on its own, and a scanned page is one big picture.
• High resolution. Scanners often save at 300–600 dpi. For reading on screen or ordinary printing, 150–200 dpi looks the same.
• Leftover data. Files edited many times can carry unused objects, embedded thumbnails and attachments.

How to compress a PDF

1. Open Compress PDF and select your file. You can add several at once.
2. Choose a level. Recommended suits most documents; Strong gives the smallest files and works well for scans; Light keeps images closest to the original.
3. Click Compress PDF and download the result. The result screen shows how much smaller the file got.

Text in the PDF stays as real text, so it stays sharp and searchable — only the images are recompressed.

If it’s still too big

• Make photos gray. Colour images take much more space than grayscale. Grayscale PDF turns images gray and leaves the text alone.
• Drop pages you don’t need. Cover pages, blank backs and appendices add up. Use Remove pages or Remove blank pages.
• Split it. Some portals let you upload several files. Split PDF can cut a document into parts under the limit.
• Send a link instead. For email, Send a PDF uploads the file (up to 20 MB) and gives you a download link that works for 7 days.

Scanning something new? Choose 150–200 dpi and black-and-white or grayscale in your scanner settings. It’s the easiest way to keep files small from the start.