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

Windows does not include a built-in PDF optimizer. Microsoft Edge can open and print PDFs, but it does not provide genuine image optimization or selectable compression levels.

Microsoft Print to PDF recreates the document instead of reliably compressing its existing PDF structure. The new file may be smaller, unchanged, or even larger. Printing can also remove bookmarks, links, forms, comments, layers, accessibility information, and digital signatures.
On Windows 11 or Windows 10, you can reduce PDF size for email with an online PDF compressor or a desktop application. 

• Free Online Tools (No Installation)

Compress a PDF online for free with PDFgear

PDFgear Online is a dedicated free PDF compressor for users who want to compress PDF on Windows without signing up. It offers Low, Medium, and Strong compression levels.

1. Open the PDFgear official website.
2. From the top menu, select PDF Online Tools > Compress PDF.
3. Click Select PDF File and choose the PDF you want to compress.
4. Select Low, Medium, or Strong, then click Compress.
5. Click Download to save the compressed PDF locally.

Start with Low compression when clarity matters and you want to reduce PDF size without losing quality as far as possible. Move to Medium or Strong only if the PDF is still too large for your email provider.

Most PDF compressors provide preset compression levels rather than a specific target size. PDFgear Online also includes a Compress PDF to 100KB tool that targets a 100 KB output, making it useful for websites with a strict 100 KB file-size limit. Select PDF Online Tools > Compress PDF to 100KB, click Select PDF File, and choose the PDF to start the compression.

Use Adobe Acrobat Online PDF Compressor

Adobe Acrobat Online is another browser-based option. It provides High, Medium, and Low compression settings, although the available workflow or download may require an Adobe account.

1. Open the Adobe Acrobat Online Compress PDF tool.
2. Click Select a file and choose the PDF.
3. Select High, Medium, or Low compression.
4. Start the compression and sign in if prompted.
5. Download the smaller PDF and inspect important pages.

Adobe handles online files on its servers. Most free online PDF compressors process only one file at a time, making them suitable for occasionally compressing a small number of PDFs. To compress multiple PDFs in one batch, use a free desktop application instead.

• Desktop applications (Offline Use)

Reduce PDF size without uploading with PDFgear Desktop

PDFgear is a free application for compressing one PDF or multiple PDF files locally. It is useful for private documents, large PDFs, or several files that need to be compressed together.

1. Open the PDFgear desktop app.
2. Select Compress PDF from the main screen.
3. Click Add Files and select one or more PDFs.
4. Select Low, Medium, or High compression.
5. Choose an output folder and click Compress to start the compression.

PDFgear does not require an account or sign-in, making it a practical choice when you need to compress PDF without Acrobat. Because all PDFgear Desktop features run locally and can be used offline, PDFs do not need to be uploaded to a server, helping protect file privacy and security.

PDFgear performs true PDF compression rather than printing each page into a replacement document. It can retain the original PDF structure and supported document elements while optimizing images and redundant data.

Use Adobe Acrobat Pro for advanced optimization

Adobe Acrobat Pro is the paid option when you need detailed control over image resolution, compression, fonts, and removable document data.

1. Open the PDF in Adobe Acrobat Pro.
2. Select All tools > Compress a PDF.
3. Open Advanced Optimization if you need detailed controls.
4. Adjust image downsampling and other settings carefully.
5. Save the optimized PDF under a new name.

Adobe Acrobat Pro cannot guarantee an exact final size. The free Adobe Acrobat Reader can open and email PDFs, but it does not include the complete PDF Optimizer controls available in the paid desktop application.

Use PDFgear Online for quick, free compression without installing software, or Adobe Acrobat Online for occasionally compressing a small number of ordinary files. Choose PDFgear Desktop when you need to batch compress PDF files offline, or compress multiple PDFs at once. Use Acrobat Pro when you need detailed control over image resolution, fonts, and removable document data.