The fastest way to comment on a PDF depends on what software you already have

You can add comments to a PDF using Adobe Acrobat Reader (free), your web browser, Microsoft Word, or the PDF editor you chose. The method changes slightly depending on which tool you use, but the basic steps are the same: open the file, find the comment tool, click where you want to mark it, and type your note. Most PDFs let you add comments without changing the original file — your notes stay separate unless you save over the document.

The tool you pick matters because some let you reply to other people's comments, some let you see comments from multiple reviewers at once, and some save comments in ways that other people can't read. If you're working alone, any method works. If you're sharing the PDF with others, you need to know whether they'll be able to see what you wrote.

Key Takeaways

  • Adobe Acrobat Reader (free) and your web browser both let you add comments without buying software, though browser comments don't always save to the file itself.
  • The Comment tool is usually in a toolbar at the top or side of the screen; click it, then click the spot in the PDF where you want to add a note.
  • Sticky note comments stay visible on the page; text box comments let you write longer notes that expand when you click them.
  • If you're sharing the PDF with others, save it as a PDF file (not Word or another format) so everyone can see the comments the same way.
  • Some PDF tools let you reply to comments and track who wrote each one, which matters if multiple people are reviewing the same document.

Adding comments in Adobe Acrobat Reader

Open your PDF in Adobe Acrobat Reader, then look for the comment tools in the toolbar. On Windows and Mac, click the "Comment" button (it looks like a speech bubble) in the top toolbar, or go to Tools > Comment. This opens a panel on the right side showing comment options.

You have two main choices: a sticky note (a small colored box that appears on the page) or a text box (a larger area where you can type). Click the sticky note icon, then click anywhere on the PDF page where you want the comment to appear. A small box opens — type your note and click outside it to save. The note stays as a small icon on the page; anyone who opens the file can click it to read what you wrote.

For longer comments, use the text box tool instead. Click the text box icon, then click and drag to create a box on the page. Type your comment inside. Text boxes are better for detailed feedback because they take up more space and are easier to read than tiny sticky notes.

Adding comments in your web browser

If you open a PDF directly in Chrome, Firefox, Safari, or Edge, you can add comments without downloading anything. The comment tools are usually in a toolbar on the right side of the screen. Look for an icon that looks like a pen, highlighter, or speech bubble.

Click the comment icon, then click on the PDF where you want to add your note. A text box appears — type your comment and press Enter or click outside the box to save it. Browser comments work the same way as Acrobat Reader comments, but they only save if you read the PDF with the comments included. If you just close the tab, your comments disappear. Some browsers let you save the annotated PDF directly; others require you to use the browser's print-to-PDF feature to keep your comments.

Browser commenting is fastest for quick feedback on a single PDF, but it's not reliable for shared work. If you're sending the file to someone else, use Acrobat Reader or a dedicated PDF editor instead so your comments definitely save to the file.

Adding comments in Microsoft Word

If you have a PDF open in Microsoft Word (Word can open and edit PDFs on Windows and Mac), you can use Word's comment feature instead of PDF-specific tools. Go to Review > New Comment, click where you want to add a note, and type your feedback. Word comments appear in a sidebar and are numbered so you can track multiple reviewers.

Word comments are useful if you're already working in Word and want to keep everything in one place. However, when you save the file back as a PDF, Word's comments don't always transfer the same way that native PDF comments do. If the person receiving the file uses Acrobat Reader or a web browser, they may not see your Word comments. Save the file as a PDF first, then use Acrobat Reader or your browser to add comments if you need to be sure others will see them.

Choosing between sticky notes and text boxes

Sticky note comments are small and don't clutter the page, making them good for quick feedback like "fix this" or "check spelling." They appear as small colored icons on the PDF, and readers click them to see the full text. Text box comments are larger and stay visible on the page, so they're better for detailed explanations or longer feedback that you want people to notice when ready.

If you're marking up a document with many comments, mix both types: use sticky notes for minor fixes and text boxes for important changes. This keeps the page readable while making sure critical feedback stands out. Some PDF tools let you change the color of sticky notes, which helps you organize comments by type (red for errors, blue for questions, green for suggestions, for example).

Saving and sharing PDFs with comments

When you add comments in Adobe Acrobat Reader or a web browser, they're usually saved to the PDF file automatically. Before you send the file to someone else, open it again to confirm your comments are there. If you added comments in Word or another program, save the file as a PDF (File > Save As > PDF) to make sure the comments transfer correctly.

When you share a PDF with comments, the other person needs software that can read PDF comments. Adobe Acrobat Reader, all major web browsers, and most PDF editors display comments the same way. Some older or very basic PDF readers don't show comments at all, so if someone says they can't see your notes, ask them to open the file in a different program.

If you want to remove comments before sharing, most PDF tools have a "delete all comments" option in the Tools or Review menu. This is useful if you've left notes to yourself that you don't want the recipient to see.

Replying to comments and tracking reviewers

Adobe Acrobat Reader and some web-based PDF tools let you reply to someone else's comment, creating a conversation thread on the page. This is helpful when multiple people are reviewing the same document. To reply, click the comment, look for a "Reply" button or field, and type your response. The reply appears indented under the original comment.

When you add a comment, some PDF tools ask you to enter your name so reviewers know who wrote each note. If you're using a shared computer or account, check that your name is set correctly before commenting. You can usually change your name in the program's settings or preferences.

If you're managing feedback from many reviewers, consider using a PDF tool that shows all comments in a list view, not just on the page itself. This makes it easier to see every note at once and track which comments you've addressed.

Frequently Asked Questions

Can I add comments to a PDF without installing software?

Yes. Open the PDF in your web browser (Chrome, Firefox, Safari, or Edge) and use the built-in comment tools. You can also use Adobe Acrobat Reader, which is free to read. Both methods let you add comments without paying for software.

Will my comments stay in the PDF if I email it to someone?

Yes, if you save the file as a PDF after adding comments. Comments are part of the PDF file itself. When you send the file, the comments go with it. The other person can open it in Acrobat Reader, a web browser, or most PDF editors and see your notes.

What's the difference between a sticky note and a text box comment?

A sticky note is a small icon on the page that people click to read your comment. A text box is a larger area where your text is always visible. Use sticky notes for quick feedback and text boxes for longer explanations or feedback you want people to notice right away.

Can I delete a comment after I've added it?

Yes. Right-click the comment (or click the menu icon next to it) and select Delete. Most PDF tools also have a "Delete All Comments" option in the Tools or Review menu if you want to remove everything at once.

What if someone can't see my comments when I send them the PDF?

Ask them to open the file in Adobe Acrobat Reader or a web browser instead of whatever program they used first. Some PDF readers don't display comments. If they still can't see them, the file may not have been saved correctly — open it yourself, confirm the comments are there, and resave it before sending it again.