You filled in a form, added a few notes and now you want to send the PDF without anyone changing a field by accident, or seeing a different result in another viewer. That is what flattening is for.

What flattening means

A PDF can hold two layers of information: the page itself, and interactive extras on top of it, such as fill-in fields, comments and stamps. Flattening merges the extras into the page so they become part of the static content. The document still looks the same, but it can no longer be edited as a form.

What Flatten PDF does

Flatten PDF rebuilds each page of your document into a new PDF at its original size. The result is a clean, non-interactive file.

Because it works this way, always check the output. Compare it with the original and confirm that:

• filled-in form values still appear
• comments and highlights you wanted to keep are visible
• signatures and stamps are where they were

Keep your original. If something you needed is missing, use the original as your working file and consider a different route, such as printing to PDF from your viewer.

When to flatten

• After filling in a form, before sending it back.
• After adding text, shapes or a signature, so they can't be moved. See signing a PDF.
• Before printing, when a printer struggles with interactive fields.
• For consistent display, when the file looks different in another viewer.
• Before archiving, to freeze a final version.

When not to flatten

• The recipient still needs to fill in the form.
• You want collaborators to add comments.
• You might need to correct a field later. Flatten a copy, not your only version.

Flattening is not redaction

Flattening does not remove information. Hidden text underneath a black box is still there, and if you need to conceal it, follow the steps in our redaction guide. Likewise, a flattened file can still be copied from, so use Protect PDF if access matters.

After flattening

Compress the file if it is bulky with Compress PDF, and add page numbers with Add Page Numbers if the document will be printed.

Frequently Asked Questions

Can I reverse flattening?

Not in the finished file. Keep the unflattened original.

Will the file size change?

It can go up or down depending on the content. Compress afterwards if needed.

Does flattening remove passwords?

Flatten a file you can open. For protected files, unlock them first with Unlock PDF if you are entitled to.

Why is some markup missing after flattening?

Interactive elements are handled differently by different software. Check the result and use the original if anything is missing.