How To Compress PDF to a Chosen Size Online

The issue? File size.

If you’re trying to compress a PDF to a specific limit, let’s say under 5 MB, 1 MB, or even 500 KB, you don’t have to waste time testing random tricks.

We’ll walk you through exactly how to compress PDF to a chosen size, using both online and built-in options for Mac and Windows.

Let’s start with the fastest and most reliable method.

How To Compress a PDF to a Specific Size: Step-by-Step Guide

The easiest way to reduce a PDF to a target size is with Compress PDF. It’s web-based, so it works on any device, and it’s designed to balance size and quality automatically.

Step 1: Go to Smallpdf Compress PDF

Open Compress PDF in your browser.

You don’t need to sign up or install anything.

Step 2: Upload Your File

Drag your PDF into the drop zone, or import it from Dropbox, Google Drive, OneDrive, or your device.

Step 3: Choose Your Compression Level

You’ll see two options:

• Basic compression: Free and perfect for everyday use
• Strong compression: Shrinks your file even more (available during free trial or with Pro)

If your PDF is only slightly too large, Basic should do the job. If you’re trying to meet a tight file limit like 200 KB or 500 KB, Strong Compression is more likely to get you there.

Step 4: Download Your Smaller PDF

Once compressed, you can download the new file or save it to the cloud. You’ll see how much space you saved right on the result page.

What Does PDF Compression Actually Do?

PDFs are more than just pages of text. They contain:

• Embedded fonts
• High-resolution images
• Background layers
• Metadata

Compression strips away what you don’t need, lowers image resolution where possible, and simplifies file structure. The result: a smaller file that still looks good.

If you're trying to hit a very specific size, you may need to compress more than once — or start with fewer images or lower-resolution content.

Compress PDF on Mac With Preview (Built-In Option)

Mac users have a built-in way to shrink PDF file size using Preview. It’s quick but less precise. How to do it: 1. Open your PDF with Preview 2. Go to File > Export 3. In the pop-up, select Quartz Filter > Reduce File Size 4. Rename the file to avoid overwriting your original, then click Save

How To Reduce PDF Size Online With Smallpdf

If you have an internet connection, the smoothest way to compress a PDF without losing quality is with Smallpdf’s Compress PDF tool. It just takes seconds, and you don’t even need to register or sign up for an account.

Smallpdf offers two options: basic or strong compression. Basic compression is completely free to use. Strong compression is free to trial, but requires a Pro account if you’ll be using it often.

How to reduce PDF file size for free with Smallpdf:

1. Go to the Compress PDF online tool.
2. Drag and drop your PDF into the box.
3. Choose either ‘Basic’ or ‘Strong’ compression.
4. Click “Compress” and wait just a second.
5. Download your PDF.

I tested it with a 235-page, graphic intensive photo book, and in a matter of seconds it reduced my PDF from 223 MB to 44 MB with Basic compression.

When I ran it through Strong compression, it compressed those 223 MB to 29 MB. Pretty impressive.

This works best for short, image-light PDFs. For my 10-page scan (with mixed text and images), the size dropped from 4.2 MB to 3.6 MB. Not a huge change, but it might be enough to pass email limits.

Downsides:

• You can’t choose how much to compress
• It may reduce quality unpredictably
• Doesn’t work well for large or complex PDFs

Still, it’s useful when you don’t have internet access or need a quick offline option.

Reduce PDF Size on Windows (No Downloads Needed)

Windows doesn’t offer a dedicated PDF compressor out of the box, but you can use two free workarounds that are built into your system.

Option 1: Print to PDF

1. Open your PDF in Edge or any PDF reader
2. Hit Print, then select Microsoft Print to PDF
3. Save the file with a new name

Sometimes this trims a few kilobytes, sometimes nothing at all. For a scanned 12-page document, the size barely changed, from 6.1 MB to 6.0 MB.

This method is hit or miss. But if you're on Windows and want to try a native approach, it’s there.

Option 2: Open in Word and Re-Save

1. Open the PDF in Microsoft Word (it will auto-convert)
2. Click File > Save As > PDF
3. Under options, choose Minimum size (publishing online)

This can help reduce size for text-based files. But it often breaks layout and formatting, especially if the PDF includes images, columns, or design elements.

Best for:

• Simple, text-only PDFs
• Quick formatting fixes before compression
• Occasional small reductions when quality isn't critical

Tips for Hitting a Target File Size

Use these tricks if you’re trying to compress your PDF to under a specific limit:

• Start with a clean file: Fewer images = smaller PDF
• Use Strong compression: Cuts more data, works better for large files
• Split the PDF: Break up large files using Split PDF before compressing
• Resize before converting: If your file came from a scanned image or camera photo, reduce image resolution first

Once you compress a file with Smallpdf, the download page will show you how much space you saved — so you’ll know if you hit your target.

FAQs

1. Can I choose the exact size I want for the PDF?

You can’t input an exact number (e.g. “make this 500 KB”), but Smallpdf gets you close by optimizing based on file type and content. Use Strong compression for tighter limits.

2. What’s the difference between Basic and Strong compression?

Basic reduces file size while keeping good quality — free to use. Strong reduces file size even more, great for scanned or image-heavy files — available with a free trial. Start your 7-day free trial today and try it.

3. Is Smallpdf safe for sensitive documents?

Yes. All uploads are encrypted with TLS, and files are deleted automatically after processing. You can also work offline using the Desktop App.

4. Does compression affect the look of my PDF?

Basic compression keeps your PDF looking nearly identical. Strong compression may slightly reduce image clarity, but keeps layout and text intact.

5. Can I compress multiple PDFs at once?

Yes. With Smallpdf Pro, you can batch compress multiple files at once. For one-off tasks, just repeat the process manually.