How to Fill a PDF Form on Your Phone (iPhone and Android)

To fill a PDF form on a phone, first check whether it has real form fields: if tapping a box brings up the keyboard, any modern viewer will do, including Preview on iPhone (iOS 26 and later), Google Drive on Android, or a browser tool. If nothing happens when you tap, the form is flat and you need a tool that lets you place text anywhere on the page.

Phone form filling fails for three reasons, and they need different fixes. The form might be flat, with no fields at all. It might be an older dynamic XFA form that most phone viewers cannot open. Or the app might save it in a way that throws your answers away. This guide shows how to tell which one you have, then how to fill, sign and send the form from an iPhone or Android phone.

Key takeaways

• Fillable forms have interactive fields; flat forms are just pictures of boxes. Adobe calls the latter "flat forms" (Adobe).
• On iPhone with iOS 26 or later, the Preview app has a Form Filling button and offers AutoFill suggestions (Apple).
• On Android, Google Drive can fill structured PDF forms, but not XFA forms, and it does not support e-signatures (Google Workspace Updates).
• For flat forms, Siliph's Fill PDF Form lets you tap any line and type, and its Detect fields option can turn printed boxes into real fields.
• If the form shows a "Please wait" message instead of the form, it is probably an XFA form; open it in Adobe Acrobat Reader on a computer or ask for another version.

Step 1: work out what kind of form you have

Adobe's explanation is the clearest: "An interactive form contains fields that you can select or fill in." But "Not all forms are fillable. Sometimes form creators don't convert their PDFs to interactive fillable forms... These non-interactive forms are called flat forms" (Adobe).

XFA forms deserve a word of warning. They were built with older Adobe form software, and mobile viewers generally cannot open them. Adobe says "XFA forms (dynamic or static forms created with Adobe LiveCycle Designer) are not supported. Acrobat cannot open these form types on mobile" (Adobe), and Google says its Drive form filling "is not available on XFA forms" (Google Workspace Updates). No phone trick fixes this reliably, so the honest answer is a computer with Adobe Acrobat Reader, or a request to the issuer for a regular PDF.

How to fill a PDF form on iPhone

iOS 26 and later: the Preview app

Apple's steps: open the PDF form in the Preview app, tap the Form Filling button, then "Tap a field, then enter information", or tap the AutoFill suggestion above the onscreen keyboard. To add a signature or a text box, tap the plus button (Apple iPhone User Guide). AutoFill can offer details such as your name and address, which saves a lot of typing on long applications.

Earlier iOS versions: Files and Markup

On earlier versions, Apple's guide says to open the document in the Files app, use Add Text Form Box for lines that have no field, and use AutoFill "as long as you've completed your My Card in the Contacts app (iOS 17.2 or later)" (Apple iPhone User Guide, iOS 17).

How to fill a PDF form on Android

Most Android phones have Google Drive installed. Google's help page describes the steps: open the PDF in Drive, tap Edit at the bottom right, then Form Filling, enter your answers, and tap Save at the top right. It adds: "If you don't see the option, you may not be able to fill out this PDF" (Google Drive Help). That usually means the form is flat or XFA.

Google's announcement of the feature also notes that it "does not support e-signature" (Google Workspace Updates), so you will need another tool if the form must be signed.

How to fill any form in your phone browser with Siliph

Siliph's Fill PDF Form opens the form in an editor with the Text tool ready. It handles both kinds of form, works the same on iPhone and Android, and is free with no account.

1. Open Fill PDF Form in Safari or Chrome and tap Choose a PDF form. Pick the file from your phone storage, Files or Drive.
2. Fillable form: tap a field and type. Tick checkboxes, choose radio buttons and pick from drop-down lists. Your values go into the form's own fields.
3. Flat form: tap the line where an answer belongs and type. The Text tool places a box there that you can drag and resize to sit on the line.
4. Lots of boxes on a flat form: choose Forms, then Detect fields. The editor finds the printed boxes and turns them into real fields, which is worth doing if you fill the same form often.
5. Signature: pick Sign, then draw with your finger, type your name or upload a photo of your signature, and drag it onto the signature line.
6. Tap Save and download the completed form. Open it once to check that every answer shows.

The form is processed on Siliph's servers: it travels over an encrypted connection, is handled automatically with no human access, and is deleted within 2 hours. Each PDF can be up to 200 MB.

Saving: why answers sometimes disappear

A filled form can look complete on your phone and arrive blank. Some viewers and printers do not draw interactive fields, so the values seem to vanish. Two habits prevent this:

• Reopen the saved copy in a different app before sending it. If your answers show there, they will usually show for the recipient.
• Flatten when the form is final. Flatten PDF draws your answers into the page itself, so every viewer shows them and nobody can quietly change them. Keep an unflattened copy if you might need to edit an answer later.

Adobe's free mobile app takes the opposite approach by default. Its help page says that with Fill & Sign, "The PDF flattens on save and cannot be edited or unsigned afterward" (Adobe). That is fine for a final submission, but keep the blank original in case you need to start again.

Before you send the form

• Attachments: if the form must go with ID scans or certificates, combine them into one file with Merge PDF. Our guide to merging PDFs on iPhone and Android covers that on a phone.
• Size limits: phone photos make files heavy. If a portal rejects the upload, see how to compress a PDF to a specific size.
• Signature rules: a drawn signature is fine for most forms, but some institutions require a certificate-based digital signature. Our guide to signing a PDF legally explains the difference.
• Building forms: if you are the one sending a form out, make it fillable with Create Forms so your recipients do not face the flat-form problem.

Frequently asked questions

Why can I not type into my PDF form on my phone?

The form is probably flat, meaning it has no interactive fields, or it is an XFA form that phone viewers cannot open. For a flat form, use a tool that places text anywhere on the page. For XFA, use Adobe Acrobat Reader on a computer.

How do I fill out a PDF form on iPhone for free?

On iOS 26 or later, open the PDF in the Preview app and tap the Form Filling button. On earlier versions from iOS 17, use the Files app and Markup. A browser tool such as Fill PDF Form also works on any iOS version.

Can Google Drive fill PDF forms on Android?

Yes, for structured fillable forms. Open the PDF, tap Edit, then Form Filling, and save. Drive does not support XFA forms or e-signatures, so use another tool for those.

How do I sign a PDF form on my phone?

Preview on iOS 26 and later lets you add a signature with the plus button. On any phone, Fill PDF Form's Sign tool lets you draw with your finger, type your name or upload a photo of your signature.

Will the recipient see my answers?

Usually, yes. To be certain, reopen the saved PDF in another app before sending, or flatten the form so your answers become part of the page and appear in every viewer.