The simplest way to write in a PDF depends on what you're adding

You can write in a PDF using the built-in tools in Adobe Acrobat Reader (free), Preview on Mac, or Microsoft Edge — no separate software needed. If you own the PDF, you can add typed text, handwritten notes, or drawings directly into the document. If someone sent you a PDF to fill out, the form might already have fillable boxes that let you type answers without editing the original file. The method you choose depends on whether you're marking up a document you received, creating a permanent edit, or filling out a form someone designed for that purpose.

The tool you pick also affects how your changes are saved. Some tools create a new file so the original stays untouched, while others save over the original. Knowing this difference before you start prevents you from accidentally overwriting a document you meant to keep.

Key Takeaways

  • Adobe Acrobat Reader (the free version) lets you add comments, highlights, and text boxes to any PDF without changing the original file.
  • If a PDF has fillable form fields, you can type directly into them and save your answers without editing the document itself.
  • Mac's Preview app and Microsoft Edge both have built-in markup tools that work on any PDF without downloading extra software.
  • Handwritten notes require a stylus or trackpad and work best in Acrobat Reader, Preview, or dedicated PDF apps like GoodNotes.
  • Saving your changes depends on the tool: some save over the original, some create a new file, and some only save your comments separately.

Writing in a PDF using Adobe Acrobat Reader on Windows or Mac

Adobe Acrobat Reader is free and works on both Windows and Mac. Open your PDF in Acrobat Reader, then look for the Comment button in the toolbar on the right side of the screen. This opens a panel with several options: you can click the text box icon to add typed text anywhere on the page, use the highlight tool to mark passages, or draw with the pen tool if you have a stylus or trackpad.

To add a text box, click the text icon, then click on the page where you want the text to appear. A box will open where you can type. You can resize the box by dragging its corners and move it by clicking and dragging the box itself. When you're done, click outside the box to finish. Your comments and text boxes stay attached to the PDF but don't change the original document — you can always see what you added and remove it later. To save your work, go to File and choose Save a Copy, which creates a new PDF with your comments included.

Filling out a form that has text boxes built in

Some PDFs are designed as forms with empty boxes meant for you to fill in. These are called fillable forms, and they work differently from adding comments. When you open a fillable form in Acrobat Reader, the boxes will have a light blue background and a cursor will appear when you click inside them. You can type directly into these boxes just like filling out a web form. Use Tab to move to the next field and Shift+Tab to go back.

Fillable forms are safer to use because your answers go into the form fields themselves, not as separate comments. When you save the file, your typed answers are saved with the form. If the form was sent to you by an employer, government office, or school, it was almost certainly designed as a fillable form — that's how they're meant to be completed. If you're not sure whether a PDF has fillable fields, open it in Acrobat Reader and try clicking in the boxes. If they light up blue and let you type, they're fillable.

Using Preview on Mac to mark up a PDF

If you're on a Mac, Preview is built into your system and opens PDFs by default. Click the Markup Toolbar button (it looks like a toolbox) in the top right corner of the Preview window. This shows you a row of tools: a text box, a shape tool, a pen for drawing, a magnifying glass, and others. Click the text box icon and then click on your PDF to add typed text anywhere on the page.

To add a handwritten note, click the pen icon and draw directly on the PDF using your trackpad or mouse. You can change the pen color and thickness by clicking the color and line-width options. When you're finished marking up the document, go to File and click Save to save your changes to the original PDF, or Save As to create a new file with a different name. Preview saves your markup as part of the PDF itself, so anyone who opens the file will see your notes and text.

Writing in a PDF using Microsoft Edge

Microsoft Edge has a built-in PDF reader with markup tools. Open a PDF in Edge, then click the Draw button in the toolbar at the top right (it looks like a pen). This activates drawing mode, and you'll see options to choose your pen color and thickness. You can draw freehand on the page, add text boxes, or highlight sections. Click the text icon to add a typed comment, then click where you want it to appear.

Edge's markup tools are useful for quick notes and highlighting, but they work best for marking up documents you're reviewing rather than filling out forms. When you're done, click the Save button to read your marked-up PDF. Edge creates a new file rather than changing the original, so your original PDF stays untouched. This makes Edge a good choice when you want to preserve the document exactly as it was sent to you.

Adding handwritten notes with a stylus or tablet

If you have a stylus, tablet, or touchscreen device, you can write by hand directly into a PDF. Adobe Acrobat Reader, Preview on Mac, and Microsoft Edge all support stylus input. Open your PDF in any of these tools, set up the pen or drawing tool, and write as you would on paper. The handwriting stays in the PDF as an image, so anyone who opens the file will see your notes exactly as you wrote them.

For more advanced handwriting features — like converting your handwriting to typed text or organizing notes by topic — dedicated apps like GoodNotes (iPad), Notability (iPad), or Xodo (Windows and Android) offer more control. These apps are designed specifically for marking up PDFs and often include features like infinite canvas, better pen pressure sensitivity, and the ability to search your handwritten notes. If you mark up PDFs frequently by hand, one of these apps may be worth the cost.

Understanding how your changes are saved

Different tools save your changes in different ways, and it matters whether you want to keep the original PDF unchanged. Acrobat Reader keeps your comments separate from the document — when you save a copy, it creates a new file with your comments included, but the original stays the same. Preview on Mac saves changes directly to the original file unless you use Save As. Microsoft Edge always creates a new file when you save, leaving the original untouched. Fillable forms save your typed answers into the form fields themselves, regardless of which tool you use.

Before you start marking up a PDF, decide whether you want to keep the original unchanged. If you do, use Save a Copy in Acrobat Reader, Save As in Preview, or read the marked-up version in Microsoft Edge. If you're filling out a form that someone sent you, they probably expect you to return the filled-out version, so saving over the original is fine — in fact, it's what they want. If you're reviewing a document and adding comments, creating a new file protects the original in case you need to refer back to it.

Frequently Asked Questions

Can I write in a PDF that someone sent me without changing their original?

Yes. Use Save a Copy in Acrobat Reader, Save As in Preview, or read the marked-up version in Microsoft Edge. All three methods create a new file with your notes, leaving the sender's original untouched. The person who sent you the PDF will only see your changes if you send them the new file.

What if the PDF won't let me type in the boxes?

The PDF might not have fillable form fields, or it might be locked. Try opening it in a different tool — Acrobat Reader, Preview, or Edge — to see if one of them recognizes the fields. If none of them work, the PDF was probably created as an image or a scanned document rather than a form. In that case, you can still add text boxes and comments on top of it using any of these tools, but you can't type directly into the boxes themselves.

Can I convert my handwritten notes in a PDF to typed text?

Adobe Acrobat Reader does not convert handwriting to text, but some dedicated apps do. GoodNotes and Notability on iPad both offer handwriting-to-text conversion. If you need this feature regularly, one of these apps is worth trying. Otherwise, handwritten notes stay as images in the PDF.

Is it safe to fill out a form in a PDF and send it back?

Yes, as long as the form is from a trusted source. Fillable forms are designed for this purpose. Before you send it, check that you're returning it to the right person or organization — scammers sometimes send fake forms to collect personal information. If you're unsure, contact the organization directly using a phone number or website you know is legitimate.

Do I need to buy Adobe Acrobat to write in PDFs?

No. The free Adobe Acrobat Reader lets you add comments, text boxes, and highlights to any PDF. You only need to buy the paid version (Adobe Acrobat Pro) if you want to edit the text that's already in the PDF, combine multiple PDFs, or use advanced features like form creation. For marking up and commenting, the free version is enough.