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How to flatten a PDF on a Mac

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To flatten a PDF on a Mac, open it in PDF Unlimited and choose File > Export Flattened…, then save the copy. Annotations, signatures and filled form fields become part of the page, so they can no longer be moved or edited. In Preview, choose File > Print, open the PDF menu and choose Save as PDF.

With PDF Unlimited (free)

  1. Finish your edits

    Fill the form, add your signature and annotations, and save the editable version first.

  2. Export flattened

    Choose File > Export Flattened…

  3. Name the copy

    Save it under a clear name, such as Application-signed-flat.pdf, so you can tell it apart from the editable original.

  4. Check it

    Open the flattened file and try clicking a form field or dragging an annotation. Nothing should move.

With Preview, built into macOS

  1. Open Print

    Open the PDF in Preview and choose File > Print.

  2. Save as PDF

    Open the PDF pop-up menu at the bottom of the dialog and choose Save as PDF. Apple notes this flattens annotations so they cannot be edited.

  3. Name and save

    Give it a new name and click Save.

What flattening means

A PDF can hold two kinds of content: the page itself, and interactive layers on top of it, like form fields, comments, highlights, text boxes and placed signatures. Those layers can be moved, edited or hidden by anyone with a PDF app.

Flattening merges the layers into the page. What you see becomes the page itself. It is a bit like printing the document and scanning it back in, without the quality loss.

When you need a flattened PDF

Flatten a copy when:

  • You are submitting a filled form, and want the answers to look identical everywhere.
  • An upload portal or older viewer shows your form blank, because it ignores fields or annotations.
  • You want a signed document where the signature cannot be dragged off or deleted.
  • You are sharing a reviewed draft and want comments to stay fixed in place.
  • A form prints with empty or gray fields. See how to print a PDF.

Flattening is not redaction

If you drew a black box over text and then flattened, the box becomes part of the page, but the text underneath can still be in the file and selectable. Flattening locks the look of a page. It does not remove what is beneath. To remove sensitive content, use true redaction.

Keep an editable original

Flattening is one-way. Once form answers are part of the page, you cannot click in and fix a typo. Always keep the editable version and treat the flattened file as the final copy you send. If you need to change something later, edit the original and export a new flattened copy.

For a tamper deterrent rather than a lock, you can also password protect the flattened file before sending.

A simple workflow for forms

For most forms you send to an employer, school, landlord or agency, this order works well:

Questions

How do I flatten a PDF on a Mac for free?

Use File > Export Flattened… in PDF Unlimited, or in Preview choose File > Print and then Save as PDF from the PDF menu.

What does it mean to flatten a PDF?

It merges form fields, annotations and signatures into the page content, so they can no longer be edited, moved or hidden.

Should I flatten a PDF form before submitting it?

It is a good idea when the form is complete and the recipient does not need to edit it. Keep an unflattened copy in case you need to fix something.

Can you unflatten a PDF?

No. Once flattened, the fields and annotations are part of the page. Go back to your editable original instead.

Does flattening a PDF hide text underneath a box?

Not reliably. Text under a shape can remain in the file. Use redaction to remove it.

Why does someone see my filled form as blank?

Some viewers and upload portals ignore form fields or annotations. Send a flattened copy so the answers are part of the page itself.