How to Add Comments to a PDF: Easy Methods & Steps

Adding comments to a PDF lets you leave feedback, questions, explanations, or suggestions without changing the document's original text.

You can add comments on desktop, online, or mobile. The best option depends on how often you review PDFs, whether the file contains sensitive information, and how you need to share the finished document.

What Is the Best Way to Add Comments to a PDF?

Choose the path based on where the PDF is stored and what the recipient needs to do with your feedback.

Situation	Recommended method	Main consideration
Regular PDF reviews	Desktop PDF editor	More complete comment tools
One-off review	Online PDF annotator	Convenient, but requires uploading the file
Basic Mac/Windows markup	Preview/Edge	Simple, but fewer review features
Quick mobile review	Apple Markup/Google Drive/Mobile PDF app	Convenient on the go, but smaller screen
Need to change document content	PDF editor	Commenting does not edit the source text

Next, let's look at how to add comments to PDFs based on different needs and in different methods with simple and easy steps.

How to Add Comments to a PDF on Desktop (Windows & Mac)

Desktop apps offer the most complete set of commenting tools. Here is how to do it on the most popular platforms, starting with the free built-in options.

Option 1: Microsoft Edge (Windows – Free, Built-in)

1. Right-click the PDF file → "Open with" → Select Microsoft Edge.
2. Look for the annotation toolbar at the top of the window. Click the "Add text" icon.
3. Click anywhere on the PDF page. A text box will appear.
4. Type your feedback, question, or suggestion.
5. Adjust the font color, size, or style using the floating toolbar (if needed).
6. Click the Save (or "Save As") button in the top-right corner.

Option 2: macOS Preview

If you only need one or two simple notes on a Mac, Preview is already installed and free.

1. Open the PDF in Preview.
2. Click Show Markup Toolbar if the tools are hidden.
3. Select the Note tool, click the page, and type your comment. You can also use the Text tool to place visible text on the page.
4. Choose File > Save or Export to keep the annotations editable.

Option 3: Add Comments to PDF with/without Adobe Acrobat

A desktop PDF editor is a good option when you need to review long documents or use several types of comments in the same file. The general process is simple: open the PDF, choose a commenting tool, place the comment next to the relevant content, and save the reviewed document.

Step 1: Open the PDF

Open the PDF in a PDF editor, annotator, or another app that supports commenting.

Step 2: Choose a Comment Tool

Select a tool such as a text comment, sticky note, text box, or callout based on the type of feedback you want to leave.

Step 3: Place the Comment

Click the relevant area of the page or text, then enter your feedback.

Step 4: Review the Comment

Check the comment for clarity and adjust its appearance or position when needed.

Step 5: Save the PDF

Save the commented PDF before sharing it with others.

The process and steps are easy and simple to follow, so the key point is to choose a better PDF editor suits your need in considering software usability, interface friendliness, and platform support, it is important to note that no single tool can meet everyone's needs; let's take Adobe Acrobat and its best alternative UPDF for the same functions but costs only 1/5 price as an example.

Here's how Adobe Acrobat add comments on PDF, click the comment icon on the toolbar then you can choose the comment type on the PDF.

Here's the steps on UPDF to add comments, you have more options to add comments like Text Box and Text Callout.

UPDF also let you export comments to a summary report, which is useful for team leads who need to review all feedback at a glance.

How to Add Comments to a PDF on Mobile

Mobile apps are useful for quick reviews, short documents, and feedback while traveling. For long PDFs or complex review workflows, a larger desktop screen is usually more efficient.

Option 1: Apple Markup on iPhone or iPad

1. Open the PDF in the Files app on your iPhone or iPad (or tap a PDF attachment in Mail).
2. Tap the Markup button (the pen-tip icon inside a circle) at the top right. This opens the drawing/annotation toolbar.
3. Tap the "+" (Add) button → Select "Text".
4. A text box will appear on the page. Tap it to edit the text and type your comment.
5. Drag the text box to the exact location you want it to sit.
6. To add a signature, tap the "+" button → Select "Signature" → Add or use an existing signature.
7. Tap Done in the top-left corner to save the changes back to the file.

Option 2: Google Drive on Android

1. Open the Google Drive app and locate the PDF file.
2. Tap the PDF to open it in Drive's built-in PDF viewer.
3. Tap the pen icon in the bottom-right corner of the screen.
4. From the bottom toolbar, select "Add text" (the "T" icon).
5. Tap anywhere on the PDF page to place a text box, then type your feedback.
6. You can also choose a highlighter or pen, but remember this guide focuses on text comments.
7. Tap the Save icon (or the checkmark) in the top-right corner to save your changes.

Option 3: UPDF Mobile for iPhone, iPad and Android

The UPDF mobile app brings the same commenting workflow to your phone or tablet, which is useful for reviewing documents while traveling or approving files between meetings.

Step 1. Open the PDF in the UPDF app on your iPhone, iPad, or Android device.

Step 2. Tap the Comment icon.

Step 3. Select Sticky Note or a text tool, tap the page where you want the comment, and type your feedback.

Step 4. To change the comment’s color or style, tap the comment and choose Properties.

Step 5. Save the file, or sync it through cloud storage so the comments appear when you reopen the PDF on your computer.

The mobile app also includes highlight, underline, strikethrough, and squiggly tools. For those, see our full guide to annotating a PDF.

How to Add Comments to a PDF Online for Free

This approach is convenient for occasional reviews because there is no desktop installation. However, consider file privacy, upload limits, and whether the service supports the comment types you need.

For a one-off, non-sensitive file, an online PDF editor works in any browser without installing anything:

1. Open an online PDF editor and upload your PDF.
2. Open its Comment tool.
3. Choose Sticky Note, Highlight, or a text tool, then click the page to place your feedback.
4. Use the reply option under existing comments if your team is reviewing the same file.
5. Download the commented PDF and reopen it to check the result.

Here are a few reliable online tools for adding comments:

• Adobe Acrobat Online: Offers standard sticky notes, highlights, and text comments with good cross-PDF compatibility.
• Smallpdf: Provides basic commenting tools with a clean, simple interface.
• Xodo Online: Includes sticky notes, text boxes, and annotation tools without requiring an account for quick use.

Which Comment Type Should You Use?

PDF apps offer several comment types. Choosing the right one keeps your feedback easy to find and easy to act on.

Comment type	What it looks like	Best for
Sticky Note	A small icon that expands into a note	Questions, suggestions, or detailed feedback that should not cover the page
Text Comment	Text typed directly onto the page	Short visible remarks or labels
Text Box	Text inside a bordered box	Instructions that must stand out on the page
Callout	A text box with an arrow	Feedback that points to an exact word, image, or area
Reply	A response under an existing comment	Team discussions and review threads

Comments are annotations: they sit on top of the page and do not rewrite the document’s original text. Use a PDF editing tool only when a correction has been approved and you have permission to change the source content.

When Are PDF Comments Useful?

Contract Review

Add a comment next to a clause to explain a concern, ask a question, or suggest a revision.

Academic Reading

Add short notes to explain key passages, record questions, or capture ideas for later reference.

Proofreading

Use comments to explain suggested changes while keeping the original text visible.

Team Review

Add comments and replies so multiple reviewers can discuss the same issue directly inside the document.

Design or Technical Review

Attach comments or callouts to a specific figure, measurement, or visual element.

PDF Comments vs. Other Annotations

A PDF comment is one type of annotation used to provide feedback, explanations, questions, or discussion.

Other annotation types include highlights, underlines, drawings, shapes, and stamps.

For example, you might highlight a sentence and then attach a comment explaining why it needs attention.

If you want to learn about the full range of PDF annotation tools, see our guide to [how to annotate a PDF].

Common Problems When Adding Comments to a PDF

Why can't I add comments to a PDF?

The PDF may have commenting restrictions, security settings, or permissions that prevent editing. Some signed or protected documents may also limit commenting.

Can I add comments to a scanned PDF?

Yes. You can generally place comments over a scanned PDF. However, if you need to select or comment on individual scanned words, OCR may be required.

Why can't someone see my comments?

Make sure the comments were saved with the PDF and that the recipient is using a PDF viewer that supports annotations.

Will PDF comments print?

It depends on the application and print settings. Check the print preview to confirm whether comments will appear on the printed page.

Can I remove comments?

Yes. Most PDF editors let you select and delete individual comments or manage them from a comment panel.

FAQS

Conclusion

The best way to add comments to a PDF depends on where the file lives: use UPDF for repeat local reviews on desktop and mobile, Preview for a quick note on Mac, and an online editor for a one-off shared file. Whichever method you choose, save a reviewed copy and check the comments in another reader before sending it.

Comments are just one part of a complete review workflow. Return to How to Annotate a PDF for highlights, drawings, stamps, and the rest of the annotation toolkit.

Download UPDF for free to add sticky notes, text comments, callouts, and markup across Windows, macOS, iOS, and Android.