What you can actually do to a PDF on a Mac

You can edit a PDF directly on a Mac using the built-in Preview app — no extra software needed. You can add text, draw, highlight, sign, and rearrange pages. You cannot change the original file unless you save your edits, and Preview will not let you edit a PDF that has password protection turned on. If you need to convert a PDF into a Word document or change its format entirely, you will need a different tool.

The most common reason people want to "change" a PDF is to fill in a form, add a signature, or mark up a document someone sent them. Preview handles all of these. If you want to do something more complex — like removing pages permanently, combining multiple PDFs, or extracting images — the steps are different and sometimes require paid software.

Key Takeaways

  • Preview is built into every Mac and can add text, signatures, highlights, and drawings to any unprotected PDF without buying anything.
  • Changes you make in Preview only stick if you save the file, and you can choose to save over the original or create a new copy.
  • To sign a PDF, use Preview's signature tool, which captures your signature from your trackpad or webcam and places it anywhere on the page.
  • If a PDF is locked or password-protected, Preview will show you that when you open it, and you will need the password or a different tool to make changes.
  • Combining PDFs, removing specific pages, or converting to another format requires either Preview's merge feature or a third-party app like PDFtk or Adobe Acrobat.

Opening and editing a PDF in Preview

Find the PDF on your Mac, right-click it, and select "Open With" then "Preview". The file opens in the Preview app. At the top of the window, click the toolbox icon (it looks like a wrench) to see your editing options. You will see buttons for text, shapes, signatures, and a drawing tool.

To add text: click the text tool (the "A" icon), then click anywhere on the PDF where you want to type. A text box appears and you can type directly into it. To change the font, size, or color, select the text first, then use the format menu at the top. To move the text box, click and drag it to a new spot.

To highlight or underline: click the highlighter or pen tool, then drag across the text you want to mark. You can change the color by clicking the color circle next to each tool. To erase a mark, use the eraser tool or press Command+Z to undo your last action.

Adding a signature to a PDF

Click the toolbox icon, then look for the signature tool (it usually shows a pen or signature icon). Click it and you will see a popup asking how you want to create your signature. You can draw it with your trackpad, use your iPhone or iPad camera to photograph your handwritten signature, or use your Mac's camera to capture you signing in real time.

Once your signature is created, Preview saves it. The next time you need to sign a PDF, you can just click the signature tool and select your saved signature from the list — it will paste it onto the page at whatever size you want. You can resize it by dragging the corners, and move it by dragging the signature itself.

Saving your changes

When you are done editing, press Command+S or go to File > Save. A dialog box appears asking where you want to save the file. By default, Preview will save over your original PDF. If you want to keep the original unchanged, click the dropdown that says "File Format" and choose "PDF", then give it a new name in the filename field.

If you close the PDF without saving, Preview will ask "Do you want to save changes?" Click "Save" to keep your edits, "Don't Save" to discard them, or "Cancel" to go back to editing. There is no autosave in Preview, so your changes disappear if you close without saving.

Combining multiple PDFs or removing pages

To combine PDFs: open the first PDF in Preview, then go to File > Open. Select the second PDF while holding Command (or Shift to select multiple files at once). Preview will add those pages to the end of the first document. You can then rearrange pages by clicking the thumbnail panel on the left side of the window, dragging pages to new positions, and deleting any you do not want.

To remove a single page: open the PDF, look at the thumbnail panel on the left, right-click the page you want to delete, and select "Delete". Then save the file. This permanently removes the page from your saved copy.

If you need more advanced combining — like inserting pages in the middle, rotating pages, or extracting specific pages into a new file — Preview can do some of this, but a dedicated PDF tool like PDFtk (free, command-line based) or Adobe Acrobat (paid) gives you more control.

When Preview cannot edit a PDF

If a PDF is password-protected, Preview will tell you when you open it. You will see a message saying the document is locked. You cannot edit it without the password. If you have the password, enter it when prompted. If you do not have it, you will need to ask whoever created the PDF or use a password-removal tool — though removing a password you do not own is illegal in most places.

Some PDFs are also locked in a way that prevents copying text or printing, even if you can view them. Preview respects these restrictions. If you need to work around them, you may need third-party software, but check whether you have permission to do so first.

Converting a PDF to Word or another format

Preview cannot convert a PDF into a Word document (.docx) or other editable formats. If you need to do that, you have a few options. Google Docs can import a PDF and convert it to editable text (though the formatting may shift). You can also use online converters like Smallpdf or IlovePDF, though these send your file to their servers. Adobe Acrobat (paid subscription) can convert PDFs to Word with better formatting preservation.

If the PDF is mostly text and you just need to copy it, you can open it in Preview, select all the text with Command+A, copy it with Command+C, and paste it into a Word document or text editor. This loses the original layout but gets the words out.

Frequently Asked Questions

Can I edit a PDF that someone emailed me?

Yes. read it to your Mac, open it with Preview, and edit it the same way you would any other PDF. When you save, you are only changing your own copy — the original stays unchanged on the sender's computer.

What if I make a mistake while editing?

Press Command+Z to undo your last action. You can undo multiple times to go back several steps. If you have already saved the file and want to start over, close it without saving the new changes, then reopen the original.

Can I password-protect a PDF after I edit it?

Preview cannot add password protection. You would need Adobe Acrobat or a free tool like PDFtk to lock a PDF. Most people do not need this for everyday editing.

Is there a way to edit a PDF on my iPhone and sync it back to my Mac?

Yes. Use the built-in Books app or iCloud Drive to store the PDF, then edit it in Preview on your Mac or in the Files app on your iPhone. Changes sync across devices if the file is in iCloud.

What is the difference between editing in Preview and using Adobe Acrobat?

Preview is free and handles basic editing: text, signatures, highlights, and page rearrangement. Adobe Acrobat (paid) adds form creation, advanced compression, batch processing, and conversion tools. For most people, Preview is enough.