QuireHow to flatten a PDF
Short answer: print the PDF to a new PDF. On a Mac, open it in Preview and choose File › Print, then Save as PDF. On Windows, print it from Edge or Chrome to Microsoft Print to PDF. The new file has your answers and markings baked into the page.
Keep the original too: a flattened copy can no longer be edited.
Updated 15 October 2026. Steps follow Apple’s Preview guide and the NIH eRA guide to flattening PDFs.
What flattening does
A filled PDF has layers: the page, plus form fields, signatures, text boxes and comments sitting on top. The NIH’s guide describes a flattened PDF as one where all the layers are merged into one flat layer, so the PDF can no longer be edited. Adobe describes it the same way.
That’s useful when:
- you’re sending a signed form and don’t want the answers changed afterwards;
- annotations should look the same in every viewer, including ones that hide comments;
- you need to combine two copies of the same form, which some tools, Quire PDF included, refuse while both have fields with the same names.
Flatten a PDF by printing it
- Fill in and mark up the PDF first
Finish your answers, signature and annotations, and save them.
- Open the print dialog
In Preview on a Mac, choose File › Print. On Windows, open the PDF in Edge or Chrome and press Ctrl+P.
- Choose a PDF output
On a Mac, open the PDF menu at the bottom of the print dialog and choose Save as PDF. On Windows, choose Microsoft Print to PDF as the printer.
- Save under a new name
Save the flattened file with a new name, such as “form – final”, so the editable original stays as it was.
- Check it
Open the new file and click a field. If you can no longer type in it, the PDF is flat.
Apple’s guide gives exactly this for Preview: to save a PDF and flatten annotations, choose File › Print, then Save as PDF. The NIH guide gives the same method on a Mac and, on Windows, printing from Edge or Chrome to Microsoft Print to PDF.
Chrome’s own Save as PDF destination also creates a new PDF from the print output, and many people use it the same way. We haven’t found an official statement on how it treats every kind of field, so use the check in the last step.
Things to know
- Flattening can’t be undone in the new file. Keep the editable original.
- Printing to PDF can drop links, bookmarks and other interactive features. That’s usually the point, but check nothing important was lost.
- Flattening isn’t redaction. Text that was covered by a box may still be in the page content. For sensitive information, use a dedicated redaction tool.
- A flattened signature is still a picture of a signature, not a certificate-based digital signature.
Where Quire PDF fits
Quire PDF, our Chrome extension, doesn’t flatten. Save a copy keeps form fields fillable and annotations editable, which is what you want while you’re still working. One place you’ll meet flattening in Quire: it won’t combine two PDFs whose form fields share names, such as two copies of the same form. Flatten one copy with the steps above, then use Manage pages › Add file to combine them. See how to combine PDFs without uploading them.
Questions
How do I flatten a PDF in Adobe Acrobat Reader?
Printing to a PDF printer works there too. Paid Acrobat has dedicated tools for it; this guide sticks to free ones.
Does flattening make the file smaller?
Not reliably. It can go either way, depending on the document.