How can I make my PDF file size smaller without losing quality?

Open your PDF in Acrobat and go to File > Save as Other > Optimized PDF. In the 'Images' section, set color/grayscale images to about 150 dpi and monochrome to 300 dpi. Choose 'JPEG quality Medium/High' (around 85%) for images. In the 'Fonts' section, select 'Subset embedded fonts' and 'Unembed fonts' if not needed. Remove unnecessary objects and user data under 'Discard Objects' and 'Discard User Data'.

What is 'downsampling' in PDF optimization and why does it matter?

Downsampling means reducing the number of pixels in an image within your PDF. It matters because fewer pixels mean a smaller file size, which helps the PDF load faster. You can control how much quality you lose by choosing the right 'dots per inch' (dpi) setting.

If my PDF is a scanned document, how should I optimize it?

If your PDF is a scanned document, you should use the 'Optimize Scanned Pages' option in Acrobat. This tool is designed to work specifically with scanned content, which often has different characteristics than digitally created PDFs. It can help clean up and compress scanned images more effectively, making the file smaller and clearer.

What is the difference between RGB and CMYK colors when optimizing a PDF for screen viewing?

Color Model Best Use File Size Impact. RGB (Red, Green, Blue) For on-screen viewing (websites, emails) Generally smaller file size CMYK (Cyan, Magenta, Yellow, Black) For professional printing Generally larger file size

Why should I unembed fonts when optimizing a PDF?

You should unembed fonts to make your PDF file smaller. When fonts are embedded, the font data is stored inside the PDF. If the viewer already has those fonts on their computer, unembedding them removes this extra data, reducing the file size. However, be careful, as unembedding can sometimes change how the document looks if the viewer doesn't have the correct fonts.

Reduce PDF file size for email or web sharing in Adobe Acrobat — How-to & AI prompts

AI prompts

3 ways to ask · copy any one

AExecute — “help me do it”Make my PDF file smaller so I can send it by…+

Please reduce the size of my PDF file so I can [email/upload/share] it easily.

when the reply comes backWant to know how to check your new file size?

BImprove — “do it better”Can you compress my PDF more without losing important…+

Can you compress my PDF even more but keep the text and images clear?

when the reply comes backNeed help finding your compressed PDF file?

CDecide — “help me choose”Should I choose higher quality or a smaller file…+

Should I choose a higher quality PDF or a smaller file size for [email/web upload]?

when the reply comes backWould you like tips for sharing PDFs online?

How to do it

the tool · the steps · what to avoid

1
Open the PDF you want to optimize in Adobe Acrobat.
2
Select File in the top menu.
3
Choose Save as Other and then select Reduced Size PDF.
CautionUsing 'Reduced Size PDF' may lower image quality or remove some features to minimize file size.
4
In the dialog box, select the desired compatibility level for the PDF (choose a later version for smaller files).
RecommendationFor maximum compatibility, select an older version; for smaller size, select the latest version.
5
Click OK to apply the size reduction.
6
Save the optimized PDF with a new file name to preserve the original.
Best practiceAlways keep a backup of your original PDF in case you need to revert changes.
7
If further size reduction is needed, go to File > Save as Other > Optimized PDF and adjust settings such as image compression and font options.
Best practiceAccording to expert blogs, reducing image resolution to 150 dpi and removing embedded fonts can significantly decrease file size while maintaining readability for web or email.

In the appWith the API

Preview your optimized PDF before sending to ensure the quality is still acceptable for your needs.

This runs in the Acrobat app - there is no separate API for this task.

Glossary

words on this page

PDFA common file type used to share documents that look the same everywhere.ExampleShe saved the brochure as a PDF so everyone would see the exact same layout and fonts.

File sizeHow much space a file takes up on your computer or phone.ExampleThe movie file had a large file size, taking up a lot of space on your hard drive.

CompressTo make a file smaller in size.ExampleYou can compress the large image file to make it easier to email.

The real tasks

the one, listed here

Replace a large hero image with a compressed version so the page loads faster for users on slow connections.

FAQ

about this task

You can use Adobe Acrobat’s 'Reduce File Size' or 'Compress PDF' option, which makes your PDF smaller so it’s easier to send or upload.

Compressing a PDF means making the file take up less space on your device, which helps when you need to email or upload it.

Most email services limit the size of attachments, so if your PDF is too large, you need to make it smaller before sending.

Sometimes, making a PDF smaller can reduce the quality of images, but you can usually choose a balance between size and quality.

For web sharing, a smaller PDF loads faster for viewers, but make sure the text and images are still clear enough to read.

Reduce PDF file size for email or web sharing

When to use it

AI prompts

How to do it

Glossary

The real tasks

Who does this

FAQ

Sources

Adobe help

Other guides

When it fails