The most direct way to edit a PDF depends on what you're changing

You can edit a PDF in three main ways: use built-in tools in Adobe Acrobat or Preview (on Mac), convert it to a different format first, or use a free online editor. Which route works best depends on whether you're changing text, adding images, filling forms, or redacting content. Some edits are simple in any tool; others require specific software.

The fastest option for most people is Preview on Mac or Adobe Acrobat Reader on Windows, both of which let you mark up and annotate PDFs without converting them. If you need to change the actual text or layout, you'll either need Adobe Acrobat Pro (the paid version) or a free alternative like LibreOffice Draw or an online editor.

Key Takeaways

  • Preview on Mac and Adobe Acrobat Reader on Windows can add text boxes, highlight, and draw on PDFs without changing the original file format.
  • To edit the actual text inside a PDF, you need Adobe Acrobat Pro, LibreOffice Draw, or an online PDF editor — the free reader versions cannot do this.
  • Converting a PDF to Word or another format, editing it there, and converting back works but may change the layout or formatting.
  • Filling forms, adding signatures, and redacting sensitive information are possible in most free PDF tools without needing the paid version.

Marking up a PDF without changing the original text

If you want to add notes, highlight passages, or draw on a PDF without altering the document itself, use the annotation tools built into Preview (Mac) or Adobe Acrobat Reader (Windows and Mac). Open the PDF, look for a markup or annotation button (usually a pen or highlighter icon), and select the tool you need.

In Preview, click the markup toolbar button in the top right, then choose from text box, highlight, underline, strikethrough, sketch, or signature. In Adobe Acrobat Reader, click the comment tool in the right panel. These changes stay with the file when you save, but they sit on top of the original content rather than replacing it. Anyone who opens the PDF will see your marks.

Editing the actual text inside a PDF

Changing the words or sentences that are already in the PDF requires software that can edit the PDF format directly. Adobe Acrobat Pro (the paid subscription) has an "Edit PDF" tool that lets you select and rewrite text, move text boxes, and adjust font size. Open the PDF, click Edit PDF in the toolbar, then click the text you want to change.

If you don't have Acrobat Pro, LibreOffice Draw (free, available for Windows, Mac, and Linux) opens PDFs and lets you edit text and objects. Open the file, double-click the text you want to change, and type. The downside is that LibreOffice may shift the layout slightly, especially in complex PDFs with multiple columns or embedded images.

Online PDF editors like Smallpdf, ILovePDF, or PDFtk also let you edit text directly in your browser without downloading software. Upload the PDF, click the text you want to change, and type. Most free versions limit the number of edits per month or file size, so check the restrictions before you start.

Converting to Word, editing, and converting back

Another approach is to convert the PDF to Microsoft Word or Google Docs, make your changes there, and convert back to PDF. This works well for simple documents with mostly text, but can scramble the layout in PDFs with images, multiple columns, or unusual formatting.

To convert, use an online tool like Smallpdf or ILovePDF (upload PDF, select "PDF to Word"), or use Microsoft Word itself (File > Open, then select the PDF). Edit the document in Word, save it, then export as PDF (File > Export As > Create PDF). This method gives you the full power of Word's editing tools but requires more steps and may need layout fixes afterward.

Adding images or replacing pages

To insert a new image into a PDF, use Adobe Acrobat Pro (Edit PDF > Add Image) or an online editor. Upload the PDF, click where you want the image to go, select the image file from your computer, and adjust its size and position. Most online editors let you do this for free within their monthly limits.

If you need to replace an entire page or add pages from another PDF, use a tool like PDFtk, Smallpdf, or ILovePDF. These let you merge multiple PDFs, delete pages, or reorder them. Upload all the files, arrange them in the order you want, and download the result.

Filling forms and adding signatures

Most PDF forms can be filled directly in Adobe Acrobat Reader (free version) or Preview. Open the PDF, click in a form field, and type. If the form has checkboxes or dropdown menus, click them to select options. When you're done, save the file.

To add a signature, use the signature tool in Acrobat Reader or Preview. You can draw your signature with the trackpad or mouse, upload an image of your signature, or type your name in a signature font. The signature appears on the PDF and stays there when you save.

Removing or hiding sensitive information

To redact text (permanently hide it so it cannot be recovered), use Adobe Acrobat Pro or an online redaction tool. In Acrobat Pro, go to Tools > Redact, select the text or image you want to hide, and apply. The content is permanently removed and replaced with a black box. In online tools, upload the PDF, select the redaction tool, highlight what you want to hide, and download.

Be careful with the free reader versions of Acrobat and Preview — they can highlight or cover text with a box, but this is not true redaction and the original content can still be recovered by someone with the right tools. If you're hiding sensitive information like Social Security numbers or financial data, use a tool that actually redacts rather than just marking over.

Frequently Asked Questions

Can I edit a PDF for free without downloading software?

Yes. Online PDF editors like Smallpdf, ILovePDF, and PDFtk let you edit text, add images, and merge files directly in your browser. Most have free versions with limits on file size or number of edits per month. No download or account is required for basic edits.

Will editing a PDF change how it looks when someone else opens it?

It depends on the tool. If you use annotations in Preview or Acrobat Reader, your marks appear on top of the original. If you edit the actual text using Acrobat Pro or LibreOffice, the changes become part of the file. Online editors usually preserve the layout, but converting to Word and back may shift text or images.

What's the difference between marking up and editing a PDF?

Marking up means adding notes, highlights, or drawings on top of the PDF without changing the original content. Editing means changing the actual text, images, or structure of the document itself. Most free tools only mark up; editing usually requires paid software or a conversion step.

Can I edit a scanned PDF or image-based PDF?

Not directly. Scanned PDFs are images, not text, so you cannot select and edit the words. You would need optical character recognition (OCR) software to convert the image to editable text first. Some online PDF editors and Adobe Acrobat Pro include OCR, but it is not always accurate, especially with poor-quality scans.

Is it safe to upload my PDF to an online editor?

Most reputable online editors (Smallpdf, ILovePDF) encrypt files during upload and delete them after a few hours. However, if your PDF contains sensitive information, using desktop software like LibreOffice or Adobe Acrobat keeps the file on your computer. Check the privacy policy of any online tool before uploading confidential documents.