What "flatten" means
A fillable PDF form has interactive boxes: text fields, checkboxes, dropdowns. They're great for filling out. But they stay editable after you're done, which causes a couple of headaches:
- Anyone can change your answers. Send a filled-in form and the person on the other end can click in and edit what you typed.
- Answers vanish in some apps. Some phone viewers, email previews and printers don't show form fields properly, so your carefully filled form shows up blank. Ugh.
Flattening fixes both. It takes whatever is in each field and stamps it onto the page as regular content, then removes the interactive field. What you see is what everyone sees, everywhere, and nobody can tweak it.
When to flatten
- Before emailing a filled-out tax form, application or registration form
- After you sign a PDF that also had fillable fields
- Before you merge PDFs that contain forms. Combining forms that have fields with the same names can cause one form's answers to show up in another. Flattening first prevents that weird glitch.
- When a form looks right on your computer but blank on someone's phone
- Before printing at a print shop
Fill it out first
This tool flattens; it doesn't fill. Open the form in your usual PDF app (Preview on Mac, Acrobat Reader, Edge, Chrome, or the Files app on iPhone all handle fillable forms), fill it out, save it, then bring the saved file here. If you skip saving, you'll flatten an empty form.
Keep an editable copy
Flattening can't be undone. Once a field is flattened, it's just text on a page. We give you a new file and never change your original, but it's still smart to keep the editable version around in case you need to fix a typo later.
What if my PDF has no form fields?
Then there's nothing to flatten, and we'll tell you so. If you're trying to make the whole document uneditable, including the regular text, that's a different job: Compress PDF on Medium redraws every page as an image, which makes casual editing a lot harder.
How to tell if a PDF has form fields
Open it in your browser or PDF reader and click on a blank line. If a text cursor shows up, or the box gets highlighted, it's a fillable field. Many readers also show a banner like "This document contains interactive form fields." If clicking does nothing, it's just a picture of a form and there's nothing to flatten. You'd fill that kind of form by adding text on top, which is what our Sign PDF tool can do.
Tips
- Check that checkboxes and radio buttons look right after flattening. Unusual custom-styled fields can occasionally look a bit different.
- Forms with fancy scripts (auto-calculating totals and the like) lose the scripts when flattened. That's fine for sending, since the numbers are already filled in.
- Add a watermark like "SUBMITTED" if you want a clear record of the final version.
Does flattening make the file smaller?
Usually a little. Form fields carry extra baggage, like the field definitions, appearance settings and sometimes scripts. Flattening strips that out. Don't expect big savings, though. For that, use Compress PDF.
Private, as usual
Flattening runs in your browser. Forms tend to be full of personal details, and none of it gets uploaded to us.