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How to sign a PDF in Gmail on iPhone

Updated October 23, 2026

The Gmail app for iPhone has no Markup or signing tool. To sign a PDF someone sent you there, save the attachment to Files, sign it with Markup in Files or Preview, then attach the signed copy to your Gmail reply. It’s free and takes a couple of minutes with apps that come with iOS. This guide uses the Gmail app. If your Gmail account is added to Apple’s Mail app instead, Mail has Markup built in (see how to sign a PDF on iPhone).

1. Save the PDF from Gmail to Files

  1. Open the Gmail app and open the email.
  2. Tap the PDF attachment to open it.
  3. You may see a Share button. Tap it, then choose Save to Files, pick a folder such as On My iPhone or iCloud Drive, and tap Save.

Google’s help page documents the share and download actions for photo attachments and Save to Drive for PDFs. It doesn’t spell out Save to Files for PDFs, and the buttons can move between Gmail app versions. If you can’t find a share option, tap Save to Drive and open the PDF from the Google Drive app instead.

2. Sign it with Markup

  1. Open the Files app (or the Preview app on iOS 26 and later) and tap the PDF you saved.
  2. Tap the Markup button.
  3. If the PDF has form fields, tap a field and type. Fill everything in before you sign.
  4. Tap the add button, then tap Add Signature. Sign with your finger and tap Done. If you already saved a signature, tap it instead.
  5. Drag the signature onto the signature line. Drag the blue dot on its bounding box to resize it.
  6. Need the date or a name next to it? Tap the add button again, tap Add Text Form Box, and type it.
  7. Tap Done.

Turning your iPhone sideways gives you more room to sign. iOS remembers your signature, and you can save more than one, such as your initials.

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3. Attach the signed PDF to your Gmail reply

  1. Go back to the Gmail app and open the original email.
  2. At the bottom of the message, tap Reply (or Reply all to include everyone on the To and Cc lines).
  3. At the top right, tap Attach, choose Files, and pick the signed PDF.
  4. Check that the attachment shows up in the reply, then tap Send.

Gmail Help documents Attach from the Compose screen. On a reply, you may see the same Attach button at the top right.

A signed contract is usually far below Gmail’s limit. A long scanned document can go over it. Gmail Help says:

  • Personal Gmail accounts: the attachment limit is 25 MB.
  • Work and school accounts: your Google Workspace administrator sets the sending and receiving limits.
  • Over the limit: Gmail “automatically removes the attachment and adds it as a Google Drive link in the email.”

A Drive link is not the same as an attached PDF. Some recipients need a real attachment for their records or e-signing system. To shrink the file first, open it in Preview, tap next to the filename, tap Export, choose PDF, and turn on Optimize Images for Screen and Save Images as JPEG. Apple notes that the first option reduces image resolution, so keep the original if the document will be printed.

Common mistakes

  • Attaching the unsigned original. If you saved the PDF twice, you can end up with two files with the same name. Rename the signed one (for example, add “signed”) so you pick the right file in Gmail.
  • Signing before filling. Fill in names, dates, and form fields first, then place the signature last, so you don’t cover text or have to move it.
  • Signature over printed text. Zoom in before tapping Done and check that the signature sits on the line without covering words.
  • Replying to the wrong address. Tap Reply all only if everyone on the thread should get your signed document. For contracts with personal details, Reply to the sender is usually enough.
  • Forgetting storage. Gmail Help notes that attachments count toward your Google storage. If your storage is full, “you can’t send or receive attachments.”

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FAQ

Can I use the Gmail app’s Save to Drive instead of Files? Yes. Gmail Help documents Save to Drive for PDFs. Open the PDF in the Google Drive app; you may see an option there to open or save it to Files, where you can sign it.