How to compress a pdf file to reduce the size before emailing on Windows?

Adobe Acrobat Pro, one of the best PDF tools available on Windows.

To compress a PDF file with Adobe Acrobat on Windows, open the PDF in Acrobat first. Then go to Menu > Save as Other > Reduced Size PDF. In the compatibility window, choose the Acrobat version you want the file to support, click OK, choose a save location, rename the file if needed, and click Save. This is the fastest way to reduce PDF size in Acrobat.

For more control to reduce the size of a PDF file, use Menu > Save as Other > Optimized PDF. In the PDF Optimizer window, choose Standard from the settings menu, then adjust options such as image downsampling, image compression, font embedding, transparency, hidden data, comments, bookmarks, and unused objects. Adobe notes that the Images, Fonts, Transparency, Discard Objects, Discard User Data, and Clean Up panels can all help reduce file size.

For scanned PDFs or image-heavy PDFs, Optimized PDF usually gives better results because most of the file size comes from large images. You can lower image resolution, use JPEG compression, and remove unnecessary metadata or embedded objects. Just avoid setting image quality too low if the PDF contains text screenshots, product manuals, invoices, or anything that must stay readable. Adobe’s PDF Optimizer is designed to balance file size and document quality through image, font, and object settings.