How to Compress a PDF File to a Much Smaller Size

September 15, 2021Ashley Mae

PDF is a widely used way to store documents, graphics, presentations, and more. It allows you to add password and give access to different groups. A document may contain several pages up to hundreds of pages. That makes many PDF files very large. It makes sense that so many people asked how to shrink PDF files on Windows, Mac or online. If you are one of them, you will find this guide pretty helpful.

Shrink PDF

Part 1: How to Shrink PDF Online for Free

Shrinking PDF is still a tough job for some people partly because of technical skill issue. Aiseesoft Free Online PDF Compressor - Best PDF Shrinkser, on the other hand, simplifies the task. It even does not ask you to install any software or pay a penny.

Key Features of Aiseesoft Free Online PDF Compressor

In brief, it is the easiest way to shrink PDF files online for beginners.

How to Shrink a PDF Online for Free

Step 1:
Open a browser when you need to shrink a PDF, copy and paste into the address bar, and hit the Enter key to open the web page.
Compressor Page
Step 2:
Click the Select PDF File button and upload the PDF that you want to shrink from your computer. Or drag and drop the file into the dotted box to upload it directly.
Process Online
Step 3:
When uploading is done, the web app will shrink PDF file size automatically. Then click the Download the PDF button to save it to your computer. Next, you can store the smaller PDF or share it online.
Download PDF

Part 2: How to Reduce PDF Size in Adobe Acrobat

Many people use Adobe Acrobat to browse, read and manage PDF documents on computer. The Pro version offers a PDF optimizer, which is able to reduce PDF file size efficiently, and more methods to decrease PDF file size.

Method 1: How to Reduce PDF Size with PDF Optimizer

Step 1:
Open Adobe Acrobat Pro. It costs $179.88 per year. Go to the File menu and choose Open option to open a large PDF file.
Step 2:
Next, click the Tools menu on the main navigation bar and choose the Optimize PDF option under the Protect and Standardize section.
Optimize PDF Adobe Acrobat
Step 3:
Now, you will be presented three different options. Select Reduce File Size or Advanced Optimization. The PDF Optimizer window will pop up.
Step 4:
Click the Audit space usage button at upper right corner to scan the unused space in the PDF. It is the easiest way to shrink PDF. Hit the OK button to remove unused space.
Optimize PDF Adobe
Step 5:
Then change the settings, such as image preferences, until you are satisfied with the shrinkage PDF. Click the OK button to confirm it.
Step 6:
Finally, export the PDF and complete the PDF shrinkage process.

Note: Adobe Acrobat Pro is expensive and it is not available to encrypted or scanned PDF documents.

Method 2: How to Reduce PDF Size by Converting Color

Step 1:
Go to the Tools window after opening the target PDF in Adobe Acrobat Pro.
Step 2:
Select Print Production and choose Convert Colors.
Print Production
Step 3:
On the popup dialog, select RGB in the Color Space field, choose FOGRA39 from the Conversion Profile option, and select All under Convert Pages section.
Colors Can be a Problem in a File Size
Step 4:
Hit the OK button to convert color and shrink the PDF.

Method 3: How to Reduce PDF File Size with Save as Other

Step 1:
After the process above, you might export the PDF. Now, go to the File menu and select Save as Other but not simply save it.
Preview Export
Step 2:
Choose Reduce Size PDF and click OK to shrink PDF further.
Save as a Reduce Size

Note: This method will reduce the image quality and remove digital signatures. If you mind it, export your PDF directly.

Part 3: More Ways to Shrink PDF on PC/Mac

How to Shrink a PDF in MS Words on PC

Some people create PDF documents in MS word. In fact, it is a versatile program. It is able to shrink a PDF file if you set it correctly. Here we show you the steps below.

Step 1:
Firstly, open the PDF file in MS Word, or open the document that you want to convert to PDF.

Tip: When open a PDF in MS Word, your document is read-only. If you want to edit it, click Enable Editing under the top menu bar.

Word PDF
Step 2:
Go to the File menu on the main navigation bar, and choose Save As. Select PDF in the Save as type menu, enter a filename and select the location folder.
Step 3:
Make sure to select the Minimum size(publishing online) option in the Optimize for section. Next, click on the Save button to confirm PDF shrink and export the smaller document.

Note: No matter you open a PDF or document in MS Word, you'd better save the result as a new file. If something is wrong, the original PDF is still here.

How to Shrink a PDF in Preview on Mac

It is well-known that the built-in Preview app is the document reader and editor on Mac. If you intend to shrink a PDF on Mac, Preview can meet your basic need.

Step 1:
Open the Finder app when you need to shrink a PDF on Mac, find the document, right-click on it, and click Open with Preview.
Open Preview
Step 2:
Next, head to the File menu and choose the Export option. Then the export dialog will pop up.
Step 3:
Enter a filename in the Export As box. Click the Where option and set the destination folder. Make sure to select PDF from the Format drop-down list. Pull down the Quartz Filter option and select Reduce File Size.
Preview Reduce
Step 4:
Click the Export button again to shrink the PDF and save it.

Part 4: FAQs about Shrinking PDF

Is it possible to shrink a PDF without losing quality?

Generally speaking, there are unused spaces and useless items. Removing them will reduce PDF size but not interrupt the quality. In fact, the tool you are using to shrink a PDF determines the output quality.

How can you reduce a PDF from MB to KB?

It might be depending on the condition of your PDF document. If it is generated by scanning, you cannot reduce the file size. For other PDFs, you can use a PDF shrinker to get smaller file size.

How to shrink a document?

There are many ways to shrink a document. The easiest one is compressing it as a ZIP archive. It won't ruin the contents in your document.


Now, you should learn at least four ways to shrink a PDF online and offline. Some of them are free of charge while others require subscription. You can pick the most appropriate way based on your situation. Aiseesoft Free Online PDF Compressor, for example, is the best option for beginners and average people. It works online and does not ask you to install on hard disk. More questions? Please feel free to leave your message below this post.

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1.1 How to Compress PDF Files 1.2 Best Solutions to Split PDF Pages 1.3 How to Reduce the PDF Size 1.4 How to Crop PDF file 1.5 Password Protected PDF File 1.6 How to add Page Numbers to PDF 1.7 How to Free Highlight Text in PDF 1.8 How to Remove Watermark in Word 1.9 How to Rotate PDF 1.10 How to add Text to PDF 1.11 Compress PDF Size on Mac 1.12 Compress PDF in Adobe 1.13 Compress PDF Online 1.14 Shrink PDF
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