3 Free and Easy Methods to Reduce Scanned Document Size Online, in Adobe Scan, or on PC

Q: I had 2 large electrical schematics I needed to scan so I could return the original documents to my customer, they are 17×22″ and 34×22″. I didn’t have time to send them out to our scanning and printing service so I scanned each one in multiple parts on our regular-sized scanner and let photoshop auto-stitch them back together. I then printed them (as a PDF in OSX) using custom paper sizes to preserve the dimensions. The resulting PDFs look good, but they’re kind of large. The big one is 37MB and the smaller one is about 7MB.

Is there some way I can reduce the file size without compromising the scan quality? The originals were a little rough to begin with so I need to be careful that they will still be legible.

– Asked by ltcarter47 from Reddit

A: We’re constantly facing situations like Itcarter47’s, where free document scanning apps such as Adobe Scan helped us scan documents, forms, and receipts to PDF, but the scanned documents are really large in file size, fairly unfriendly to electronic submission or Email transmission.

If you’re baffled by that issue, then this post will definitely bail you out. In this post are three easy, working, and practical methods to compress the file size of your scanned documents from scanners.

All introduced methods are completely free and safe, so make sure you follow the step-by-step tutorials and have a try on your own!

More PDF How-tos: Compress PDF to 300 KB or Less, How to Present a PDF, Convert Word to JPG Online

Method 1. How to Reduce Size of Scanned Document with Adobe Scan

This method requires the use of Adobe Scan, the fairly popular document-scanning tool for Android phones and iPhones. It’s not possible to compress PDF in Adobe Scan, as it doesn’t offer such kind of functionality (while Adobe Acrobat does). However, there is still a way to reduce the size of a .pdf file while scanning in Adobe Scan, the workaround is as follows.

Step 1. Launch Adobe Scan App on Your Mobile

To reduce the size of a scanned document, launch Adobe Scan on your mobile phone.

If you haven’t installed Adobe Scan already:

– Get Adobe Scan from Apple Store

– Get Adobe Scan from Google Play Store

Step 2. Import the Document File

If you haven’t scanned the document already, scan it with Adobe Scan.

And if you have the scanned document on your mobile already, add the document you intend to resize to Adobe Scan app from your camera roll or your mobile device storage.

Step 3. Resize the Dimension of the Document

Use the Adobe Scan crop feature, the second left option from the main workplace, to remove any unwanted part from the border of the scanned document, which would take up redundant storage space if not. Be careful not to crop out anything important!

Step 4. Save the Scanned Document as PDF

After resizing the border of the scan, hit the Save PDF button from the upper-right side of the workplace to save the scanned document as a PDF.

Step 5. Save the Resized Document as JPEG

Lastly, save your document as JPEG (JPG), and you’ll find it in your camera roll. After that, the output JPG file will have a remarkably smaller size than the original PDF scan.

This method applies to cases where you don’t care about the document file format, but if want your file to stick to a PDF document, the smart way comes up.

Method 2. The Smart Way – How to Reduce Scan PDF File Size Online with PDFgear

Fancy a tool for reducing scanned PDF file size and exporting in PDF file format? We’ve got you. Introducing PDFgear, the best online PDF compressor tool that allows you to fast compress scanned PDF documents in a simple drag-and-drop manner.

Powered by MRC technology, PDF gear even allows for extreme PDF conversion, while maintaining the quality and readability of the original PDF. PDFgear fast reduces your scanned PDF files to 144 dpi to better fit Emails.

PDFgear is completely free, TLS encrypted, and watermark-free. And as a cross-platform online service, PDFgear works on popular operating systems including Windows 10, Windows 11, Windows 7, Mac, Chrome, laptops, Android, iOS, etc. Thus you can easily reduce the size of scanned document PDFs on whatever device you’re on.

Step 1. Upload Scanned Document PDF

Navigate the PDFgear PDF compressor, if you’re on a desktop, drag and drop the document file into the compressor. And if you’re on mobile, hit the Choose files button to upload your PDF document from your device.

Step 2. Reduce Size of Scanned Document with PDFgear

Wait one second for the uploading process, and choose a preferred compression mode from Low compression, Medium compression, and Strong compression. The smaller the output file size, the lower the quality.

Step 3. Download the Compressed Scanned Document

When the blue Download button becomes visible, hit it to download the highly compressed PDF document, the size of the compressed document scan will be shown under the filename of the document.

If you go with low or medium compression, you’ll find the document maintaining the original quality.

Method 3. How to Compress Scanned Documents Offline with PDFgear Desktop

PDFgear Desktop is the ultimate PDF solution for desktop workers. The PDFgear Desktop is a robust desktop PDF converter as well as a compressor that features a high compression ratio without compromising PDF quality, faster and steadier compression/conversion, and support for bulk compression.

And can help you get your Adobe Scan PDF documents under 50~100 KB a page, and around 20 MB in total, which would be perfect as Email attachments. And there are more features waiting for you to find out.

Now hit the Download button above to get PDFgear for free on your Windows or Mac PC!

Step 1. Upload the Scanned PDF Documents

Launch PDFgear, and then open the PDF compression tool. Upload the PDF file by tapping the “Add Files” button. You can also select multiple files at once by pressing the Ctrl key continuously.

Step 2. Select A Compression Level

Below the window are three compression levels: Low, Medium, and High. A higher compression level results in a smaller file size. Next, choose a location for the output.

Step 3. Compress the PDF File Now

Once you have made your decision, click the red Compress button.

On the pop-up file Explorer, the reduced PDF file will appear after a few seconds.

Why is My Scanned Document Size So Large?

The fact that your scanned PDF documents are really large in size can result from that you have scanned them at a high DPI. DPI, aka Dots Per Inch, is a measure of spatial printing, video, or image scanner dot density, gauging the number of dots in the scope of 1 inch.

The higher the DPI, the finer the details of the print, and you may have inadvertently set an unnecessarily high DPI value while scanning.

However, a DPI value over 300 could be overkill for text files and brings about large document file storage sizes.

To avoid the huge size of scanned document PDF for a text file, the smart move is to set the DPI value at around 200~250 while scanning or reduce the document PDF size with a decent PDF file size reducer such as PDFgear, which is able to maintain the document quality.

To Sum Up

As there’re three excellent methods provided, I believe you have found one that suits you and have followed the tutorial to reduce scanned document PDF to a smaller size. PDFgear will fit right in with your work routine, and you’ll be impressed by its steady performance!

Moreover, the PDF reading and PDF editing feature that PDFgear offers will definitely be a terrific help for your work and document management. So please make sure to give PDFgear a try! And if you have trouble using PDFgear or any insights you’d like to share, please leave us a message in the comment section below.

Hint: Please do not confuse the “reduce file size/resizing file” referred to in this post, as in reducing the file size that it occupies on your device storage space, with the resizing as in resizing the scanned document dimension.

To resize the dimensions of the scanned document, you can simply go to the Adobe Scan app > Tap the “Modify” option > Tap the ” Resize” button.