How to flatten a PDF
Quick answer: To flatten a PDF form, open it in an editor like Quick PDF, fill in the fields, then choose Flatten form when you download. Flattening turns your typed answers, checkmarks and dropdown choices into part of the page, so they display the same in every PDF viewer and can no longer be edited as form fields.
Sign in with Google or email and start editing. Saving your file starts a free trial: 7 days on yearly ($29.78/yr) or 2 days on monthly ($2.99/mo). Cancel anytime. 🔒 Your file stays on your device.
"Please send a flattened PDF" is a common request from HR teams, schools, landlords and government offices. It sounds technical, but it simply means: make the filled-in answers a permanent part of the page instead of editable boxes.
This guide explains what flattening does and does not do, how to flatten a form in Quick PDF on any device, when you should and should not flatten, and other ways to make a PDF harder to change.
Flatten a PDF form with Quick PDF
- Open the PDF in Quick PDF Go to quickpdfapp.com, sign in, and open the fillable PDF from your device.
- Fill in and check every field Tap each box to type, tick checkboxes, choose dropdown options, and fix any mistakes now, because flattened answers cannot be edited as fields.
- Add a signature or extra text if needed Use Sign for your signature and Add text for dates or notes.
- Tap Download and choose Flatten form Select the Flatten form option so the answers become part of the page.
- Check the flattened copy Open the downloaded file and tap a field: it should no longer show a cursor, and the answers should look exactly as you typed them.
What flattening a PDF actually does
A fillable PDF has two layers of information: the page itself, and interactive form fields that sit on top and hold your answers. Flattening merges the answers into the page and removes the interactive fields.
| Fillable (not flattened) | Flattened | |
|---|---|---|
| Answers can be changed by typing in the box | Yes | No |
| Looks the same in every viewer | Not always | Yes |
| Checkboxes and dropdowns | Clickable | Shown as they were chosen |
| Recipient can read the data automatically as form data | Often | No |
| Text on the page still selectable | Yes | Usually yes |
Flattening is not a security feature. It stops accidental changes, but someone with a PDF editor could still add text or cover things on top of the page.
When to flatten (and when not to)
Flatten when:
- You are sending a finished form to an employer, landlord, school, bank or government office.
- The form will be opened on many different devices and you want it to look identical everywhere.
- The recipient specifically asked for a flattened PDF.
- You are combining a filled form with other files and want answers to stay visible.
Do not flatten when:
- You will need to update the answers later. Keep a fillable copy for yourself.
- The recipient's system reads form fields automatically and asked for an editable PDF.
- Someone else still has to fill in their part of the form.
Flattening on phone and computer
The steps are the same everywhere because Quick PDF runs in your browser: fill the form, tap Download, choose Flatten form. On an iPhone the flattened file goes to your Files app (or straight to Mail or Messages if you use Share); on Android it usually lands in Downloads; on a computer it goes to your Downloads folder.
Filling the form itself is covered in how to fill out a PDF form and save it, and on iPhone in fill out a PDF on iPhone.
Other ways a PDF gets flattened in Quick PDF
- Merging: when you combine files with Merge, form fields are flattened in the combined file. Fill and check forms before merging.
- Redact: pages you redact are rebuilt as images so the hidden text is truly gone. Those pages are flattened completely, and their text is no longer selectable.
- Compress on Smallest: every page becomes a compressed image, so nothing on the page can be selected or edited as text afterward. Use it only when file size matters more than selectable text.
Making a PDF harder to change or read
People often search for "flatten" when what they really want is to stop others changing a document or seeing it. Options in Quick PDF:
- Flatten form: locks answers against accidental edits.
- Protect: adds a password with AES-256 encryption, so the file cannot be opened without it. See how to send a PDF securely.
- Redact: permanently removes sensitive text you do not want anyone to see.
Quick PDF does not set separate "no editing" or "no printing" permissions. For legal certainty that a file was not changed after signing, people use certificate-based digital signatures, which Quick PDF does not create; see electronic vs digital signature.
Other ways to flatten a PDF
Printing a PDF to a new PDF ("Save as PDF" or "Microsoft Print to PDF" in a print dialog) often flattens form fields too, though results vary between apps and some lose quality. Desktop PDF software from other makers usually includes a flatten option as well. Quick PDF keeps it to one choice at download time, on any device, with your file processed in your browser on your device.
Troubleshooting
My answers disappeared after flattening
The answers were probably not saved in the fields before downloading, which can happen if the form was filled in a viewer that did not save them. Fill it again in Quick PDF and download with Flatten form.
I flattened too early
Open the original fillable file again, make your changes, and download a new flattened copy. If you only have the flattened file, use White-out and Add text to correct an answer.
The recipient says the form is not fillable
That is what flattening does. If they need an editable form, send the copy you downloaded without Flatten form.
Questions people ask
What does it mean to flatten a PDF?
It means merging filled form fields and their answers into the page itself, so the answers become fixed content instead of editable boxes. The document then looks the same in every PDF viewer.
How do I flatten a PDF on my phone?
Open the form in Quick PDF in Safari or Chrome, fill it in, tap Download and choose Flatten form. The flattened copy is saved to your Files app or Downloads, or you can use Share.
Does flattening a PDF make it uneditable?
It removes the editable form fields, so answers cannot be changed by typing in the boxes. Someone with a PDF editor could still add text on top, so flattening is about preventing accidental changes, not security.
Can I unflatten a PDF?
Not really. Once fields are merged into the page, the original form fields are gone. Keep a fillable copy before flattening in case you need to make changes.
Should I flatten a W-9 or job application before sending it?
Usually yes, unless the requester asked for an editable PDF. Flattening keeps your answers visible and unchanged in whatever viewer they use.
Does flattening reduce file size?
Sometimes slightly, but not reliably. If you need a smaller file, use Compress instead.
Do I have to pay to use Quick PDF?
You can open a PDF and edit, sign or fill it after signing in with Google or email. To download, print or share the finished file you start a subscription with a free trial: 7 days on the yearly plan ($29.78 per year) or 2 days on the monthly plan ($2.99 per month). You are charged when the trial ends unless you cancel, and you can cancel anytime.
Sign in with Google or email and start editing. Saving your file starts a free trial: 7 days on yearly ($29.78/yr) or 2 days on monthly ($2.99/mo). Cancel anytime. 🔒 Your file stays on your device.