How can I reduce the file size of a PDF without losing too much quality in Adobe Acrobat?

Open your PDF and go to File > Save as Other > Optimized PDF. In the Optimizer, adjust 'Images' settings. Aim for color/grayscale images at ~150 dpi and monochrome at 300 dpi. For JPEG quality, 'Medium/High' (around 85%) is often a good balance. Also, check 'Fonts' to subset or unembed if possible, and 'Discard Objects' to remove unneeded elements.

What is the difference between 'subsetting' and 'unembedding' fonts when optimizing a PDF?

Feature What it does Impact on File Size Risk to Text Appearance. Subsetting Fonts Embeds only the characters used in the document, not the whole font. Good reduction, keeps text looking correct. Very low, as characters are still embedded. Unembedding Fonts Removes all font information from the PDF. Larger reduction, but relies on viewer's system fonts. High, text may display differently if the font is not available.

Reduce Design-Engineering Iterations in Adobe Acrobat — How-to & AI prompts

AI prompts

1 way to ask · copy any one

DBecome — “help me grow”Over the past year my handoffs produce three rounds of clarification on average, costing two…+

Over the past year my handoffs produce three rounds of clarification on average, costing two weeks each time. Show where in my send method the time drains (attachments, unclear asks, too many reviewers) and propose one change to my default send that will cut clarification rounds in half. Include how to phrase the request so engineers can answer with 'OK to tool' or provide a single prioritized blocker.

when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed.

How to do it

the tool · the steps · what to avoid

1
Open your PDF file in Adobe Acrobat.
2
Select the File menu, then choose Save as Other and then Optimized PDF.
3
In the PDF Optimizer dialog, review the default settings under each panel (such as Images, Fonts, Discard Objects, Discard User Data, and Clean Up).
4
Adjust any settings as needed, or leave them at their defaults for a basic optimization.
5
Click OK to apply the optimization and choose a location to save the optimized PDF.

In the appWith the API

You can preview the estimated file size reduction before saving by clicking the 'Audit space usage' button in the optimizer dialog.

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

Glossary

words on this page

DownsampleTo make an image smaller by removing some of its detail, which reduces the file size.ExampleTo make a large photo fit an email, you might downsample it to reduce its file size.

Unembed FontsTo remove font files from the PDF so it uses less space.

OptimizeTo make something work better for a specific use.ExampleYou optimize your website images to load faster for visitors with slower internet connections.

Who does this

3 roles

Graphic DesignerAdministrative AssistantMarketing Coordinator

FAQ

about this task

Open your PDF and go to File > Save as Other > Optimized PDF.
In the Optimizer, adjust 'Images' settings. Aim for color/grayscale images at ~150 dpi and monochrome at 300 dpi.
For JPEG quality, 'Medium/High' (around 85%) is often a good balance.
Also, check 'Fonts' to subset or unembed if possible, and 'Discard Objects' to remove unneeded elements.

Downsampling means reducing the number of pixels in an image. When you downsample images in a PDF, you make the file size much smaller. It matters because fewer pixels mean less data, which makes the PDF easier to share and faster to open, but too much downsampling can make images look blurry.

For PDFs with many scanned pages, Adobe Acrobat has a special tool called 'Optimize Scanned Pages'. You should use this feature because it is designed to handle the unique characteristics of scanned documents, often improving both file size and clarity more effectively than the general PDF Optimizer. It helps with text recognition and image cleanup specific to scans.

It's important to use RGB (Red, Green, Blue) color mode for PDFs viewed on screens because computer monitors display colors using RGB. CMYK (Cyan, Magenta, Yellow, Black) is for printing. Using RGB ensures your colors look accurate on screen and helps keep the file size smaller, as CMYK often contains more data than needed for digital display.

Feature	What it does	Impact on File Size	Risk to Text Appearance
Subsetting Fonts	Embeds only the characters used in the document, not the whole font.	Good reduction, keeps text looking correct.	Very low, as characters are still embedded.
Unembedding Fonts	Removes all font information from the PDF.	Larger reduction, but relies on viewer's system fonts.	High, text may display differently if the font is not available.

Reduce Design-Engineering Iterations

When to use it

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The real tasks

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Sources

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When it fails