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Underline PDF Like a Pro: Your Ultimate Guide for Windows, Mac, iOS, and Android

Welcome to our comprehensive step-by-step guide on how to underline in PDF documents on Windows, Mac, Android, and iOS. Whether you need to emphasize key points, highlight essential information, or add clarity to your PDFs, underlining text can be a powerful tool. In this guide, we'll walk you through the process of underlining text in PDF.

How to Underline in PDF on Windows and Mac?

To underline in PDF, you need a great PDF editor. UPDF is a great and powerful PDF editor that you may need. With it, you can not only underline PDF, but also effortlessly annotate PDFs, edit text and images, organize and convert PDF pages, utilize OCR, and access files through UPDF Cloud. Whether you're on Windows or Mac, UPDF can underline important text in just a few simple steps. Moreover, it has OCR feature, so if you want to underline the text in scanned PDF, you can do it. So, in this guide, we will show you how to underline in normal PDF and scanned PDF.

Way 1. How to Add Underline in Normal PDF on Windows and Mac?

To underline text in a normal PDF on both Windows and Mac using UPDF, follow these steps:

  • Click the below button to download UPDF. Open the PDF document you wish to underline text in.

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  • Locate the "Comment" icon on the left toolbar and click on it.
  • From the markup options on the top toolbar, select the underline symbol to enable the underline feature.
  • Once the underline feature is activated, hover your cursor over the text you want to underline.
  • To customize the underline color, double-click on the underline option and choose the desired color from the available options.
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Way 2. How to Underline Text in a Scanned PDF on Windows and Mac?

To underline text in a scanned or image-based PDF, you can use UPDF's OCR feature, these are the simple steps you need to follow!

  • Open your scanned PDF in UPDF and hit "Recognize Text Using OCR". 
  • In the popping-up menu, select the layout, set your language from one of the 38 supported ones, and select the page range if you need it.
  • Hit "Perform OCR" to convert your scanned PDF into the edited one. 
  • Once done with the conversion, the ocred PDF will open automatically on UPDF. Then, follow the same steps as in the above guide to underline text in your recently converted PDF. 
underline scanned pdf

How to Underline in PDF on iPhone and iPad?

If you need to underline in PDF on iPhone and iPad, UPDF for iOS can also work for you. Here are the steps to do it:

  • Open the UPDF application on your device.
  • Open the PDF document you wish to annotate.
  • You'll see a pencil icon, tap on it, and it'll reveal all the annotation tools.
  • Tap on "Markup" and select the underline option.
underline text in pdf on ios
  • Now all the markup tools will be revealed. You can choose the underline icon at the bottom.
  • Hover your finger over the text you want to underline and save your changes.
underline pdf on iphone and ipad

How to Underline in PDF on Android?

If you are using an Android device, you can follow the instructions below to learn how to underline text in PDF on Android using UPDF:

  • Launch the UPDF app on your Android device.
  • Open the PDF document you want to underline.
  • Tap on the "Pen" icon and then the "Markup" icon located at the top of the interface.
  • Select the underline option from the available markup tools.
  • Hover your finger over the text you wish to underline to highlight it.
  • For further customization, long-press the underline option to choose a different color or thickness.
underline pdf on android

It is easy to underline text in PDF with UPDF. So, we highly recommend you download UPDF to test it on your own. And if you want to know more about UPDF, you can read this review article from Howtogeek or watch the below video.

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FAQs on Underline in UPDF

Here are some FAQs regarding underlining PDFs:

Q1. Why Can't I Underline a PDF?

There are several reasons why you may be unable to underline text in a PDF. One common reason is that your PDF might be scanned which does not allow you to edit the PDF. So you cannot underline it. To overcome this limitation, you would need to utilize OCR (Optical Character Recognition) technology which allows you to convert scanned PDFs into editable and searchable text. Then, you can underline a PDF.

The second reason is that your PDF is password-protected. In this case, you need to enter the password, then, underline PDF text.

Q2. How to Change Underline Color in PDF?

To change the underlined color in PDF, you need to use UPDF. Open the PDF with underlined texts. Then, go to "Comment", click on the underline, choose the color picker in the pop-up menu, and select the color you need. Nore, you change the underlined color in PDF successfully.

Q3. How to Remove Underline from PDF Online?

There are no effective ways to remove underline from PDFs online. So, you can use one offline tool. We recommend you use UPDF as it is easy to use. What you need to do is open the PDF with the underline, click the "Comment", then, the underline, and click "Delete" to remove the underline from the PDF.

Q4. How to Underline Text in PDF Form?

To underline text in PDF form, you need to click the below button to download UPDF on your device. Open PDF form with UPDF, click on the "Comment" > "Underline" and move your mouse to underline the text on your PDF FORM.

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Q5. How to Underline PDF Online?

You can use PDFbob to underline PDFs online. Just click here to visit PDFbob online PDF editor, upload the PDF, click on "Annotate" > "Underline" > pick the color and underline the text in the PDF. Now, click "Done" > "Export" to save it.

Q6. How to Underline Text in PDF with Adobe Reader?

Adobe Reader has the features to underline text in PDF. You can open the PDF with Adobe Reader, click on the third icon at the left side menu, and choose "underline". You can pick up the color you need to underline the text in PDF. Once done, save the PDF via "File" > "Save".

Benefits of Underling Text in PDF

Underlining text in PDF documents offers numerous benefits that enhance readability, emphasize key information, and improve overall document comprehension. Whether you're a student, professional, or avid reader, underlining text in PDFs can greatly enhance your reading and studying experience. Let's explore the benefits in more detail:

Emphasize Important Information

You can highlight and draw attention by underlining crucial points, key concepts, or essential details within the document. By visually emphasizing specific text, you can quickly and easily identify and remember important information.

Enhance Readability

Another benefit of underlining text is that it improves the readability of PDF documents, making it easier to skim through and navigate the content. The underlined sections stand out from the rest of the text, providing visual cues and guiding the reader's attention.

Study and Research Aid

By underlining your text in a PDF document, you can keep your PDF organized and categorize information, making it easier to review and revisit important points. By underlining in PDFs, you can create concise summaries, extract key ideas, and effectively annotate your study materials.

Document Annotation

Underlining serves as a form of annotation, allowing you to mark up PDFs and add your insights or thoughts directly onto the document. This makes it convenient for personal note-taking, collaborative work, or sharing feedback on drafts and reports.

Efficient Document Review

When reviewing lengthy PDF documents, underlining important text enables quick referencing and efficient information retrieval. It saves time by allowing you to locate and review key sections without reading the entire document.

Visual Organization

By underlining text, you can visually organize information within a PDF. This is especially helpful for categorizing ideas, creating hierarchies, or distinguishing between different types of content. It provides a clear structure and improves the overall visual appeal of the document.

Improved Document Navigation

When revisiting PDFs at a later time, underlining helps you navigate through the document more effectively. By underlining significant sections, you can easily skim and find the specific information you need without having to go through the entire document again.

Compatibility and Portability

Underlining in PDFs ensures that the annotations and underlined text remain intact when sharing or transferring the document across different devices or platforms. This makes it easy to access and review your underlined PDFs on various devices and with different PDF readers, including UPDF.


Wrap Up!

Underlining text in PDF documents is a valuable feature that enhances readability and emphasizes important information. With UPDF, you can easily underline text in PDFs using the intuitive interface and powerful annotation tools.

Download UPDF via the below button and follow these step-by-step instructions, you can effortlessly underline text in your PDFs, making them more engaging and impactful. Also, UPDF has a big sale on its pricing, so seize the opportunity and purchase it now!

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