How to Sign a PDF on Your Phone (iPhone & Android)

You are at a coffee shop, at the airport, or sitting on your couch when an email arrives with a PDF that needs your signature urgently. You do not have access to a computer. All you have is your phone.

Good news: signing a PDF on your phone is not only possible, it is easy. In fact, your phone's touchscreen might give you a more natural-looking signature than any laptop trackpad ever could.

This guide covers the best methods for signing PDFs on both iPhone and Android, including native tools and the browser-based SigPDF. It also includes practical tips for getting clean, professional-looking signatures from a small screen.

Method 1: Signing a PDF on iPhone (Using Markup)

Apple's built-in Markup tool works across the iOS ecosystem and provides a quick way to sign PDFs without installing anything.

Step-by-Step

1. Open the PDF. You can open it from Mail, Files, Messages, or any app that handles PDFs. If the PDF is an email attachment, tap it to preview it.

2. Tap the Markup icon. It looks like a pen tip in a circle, usually in the top-right corner of the preview screen. If you opened the file in the Files app, tap the Markup icon in the toolbar.

3. Tap the "+" button in the markup toolbar at the bottom of the screen, then select "Signature."

4. Create your signature. If you have not saved a signature before, you will be prompted to draw one using your finger on the screen. Sign in the space provided and tap "Done." If you have a saved signature, it will appear as an option to select.

5. Position and resize. Your signature appears on the document. Drag it to the correct location and use the corner handles to resize it so it fits the signature line.

6. Tap "Done" to save the signed PDF. You can then share it via email, AirDrop, or save it to Files.

Pros

• Built into every iPhone — no download required
• Saves your signature for future use
• Works offline
• Integrates with the entire iOS sharing ecosystem

Cons

• Limited to drawn signatures only (no typed option)
• Positioning can feel imprecise on smaller iPhone screens
• No advanced features like text fields or date stamps
• Only available on Apple devices

Method 2: Signing a PDF on Android (Using Google Drive)

Android does not have a single universal built-in PDF signing tool like iOS, but Google Drive provides basic annotation capabilities on most Android devices.

Step-by-Step

1. Open the PDF in Google Drive. Upload the file to Google Drive if it is not already there, then open it in the Google Drive app.

2. Tap the annotation/edit button. Tap the pen or edit icon to enter annotation mode.

3. Select the pen tool and use your finger to draw your signature directly on the document where it needs to go.

4. Adjust if needed. You may need to zoom in to place your signature precisely on the signature line.

5. Save and share. The annotated PDF can be saved and shared from Google Drive.

Note: The Android annotation experience varies by device and Android version. Some Samsung devices have their own PDF markup tools through Samsung Notes or the built-in PDF viewer that may work better.

Pros

• Available on most Android devices through Google Drive
• No additional app installation needed
• Syncs with your Google account

Cons

• The annotation experience is basic and varies by device
• Drawing precision can be inconsistent
• Requires a Google account and internet connection for Drive
• Not designed specifically for signing — more of a workaround

Method 3: Using SigPDF on Any Phone (Recommended)

SigPDF works in any mobile browser — Safari on iPhone, Chrome on Android, or whatever browser you prefer. It provides a purpose-built signing experience that is optimized for mobile use.

Step-by-Step

1. Open your mobile browser and navigate to sigpdf.com. No app installation needed.

2. Upload your PDF. Tap to browse your files and select the PDF, or use your phone's share sheet to open the file in the browser. The document loads in a mobile-optimized viewer.

3. Create your signature. You have three options:

   • Draw: Use your finger to sign directly on the screen. The touchscreen gives you natural, fluid strokes that closely resemble your real signature.
   • Type: Enter your name and choose a handwriting-style font. This is the fastest option and always looks clean.
   • Upload: Select a saved image of your signature from your camera roll.

4. Place your signature. Tap on the document where the signature belongs. Pinch to resize and drag to reposition until it fits perfectly.

5. Download. Tap download and the signed PDF is saved to your phone. From there, you can email it, share it, or save it to your cloud storage.

Pros

• Works on any phone with any browser — iPhone, Android, or anything else
• Three signature methods (draw, type, upload) give you flexibility
• Client-side processing means your PDF never leaves your phone
• No account, no app installation, no storage permissions
• Purpose-built for signing, so the interface is focused and intuitive
• Mobile-optimized layout that works well on small screens

Cons

• Requires an internet connection to load the web app
• Does not save your signature between sessions

Tips for Getting a Great Signature on Your Phone

Signing on a phone screen has its challenges — it is small, your finger is not a pen, and autocorrect cannot help you here. These tips will help you get a professional result:

1. Hold Your Phone in Landscape Mode

Rotate your phone sideways when drawing your signature. This gives you more horizontal space, which matters because most signatures are wider than they are tall. Many signing tools, including SigPDF, respond well to landscape orientation.

2. Use Your Fingertip, Not Your Nail

The capacitive touchscreen on your phone responds to the fleshy pad of your fingertip. Using your nail will produce inconsistent, skippy lines. Press gently with the pad of your index finger and sign at a moderate speed.

3. Practice on a Blank Area First

If the signing tool has an undo button, take a practice run before committing. Sign once, evaluate it, undo, and sign again. Your second or third attempt will almost always look better than your first.

4. Consider a Typed Signature

There is no rule that says your electronic signature must look like your handwritten one. A typed signature in a clean script font often looks more professional than a shaky finger-drawn signature. SigPDF offers multiple font options that produce excellent results.

5. Use a Stylus for Precision

If you sign PDFs frequently on your phone, a basic capacitive stylus — available for under $10 — dramatically improves the quality of drawn signatures. It gives you the control of a pen without the limitations of finger input.

6. Zoom In Before Placing

Pinch to zoom into the signature area of the document before placing your signature. This makes it much easier to position the signature precisely on the line, avoiding the common problem of a signature that is slightly above, below, or offset from where it should be.

7. Check the Final PDF

After downloading, open the signed PDF and scroll through it to make sure the signature is positioned correctly, the right size, and clearly visible. It takes ten seconds and prevents the embarrassment of sending a document with a misplaced signature.

Which Method Should You Use?

For most people signing a PDF on their phone, SigPDF offers the best combination of quality, privacy, and convenience:

• It works on both iPhone and Android without any app installation
• It offers typed signatures for a consistently clean look (something the native iOS and Android tools lack)
• It processes your document entirely on your device, so sensitive PDFs are never uploaded to a server
• It requires no account, so you can sign and be done in under a minute

The native methods (iOS Markup and Google Drive on Android) are useful fallbacks when you are offline or want to avoid opening a browser, but they provide a more limited experience.

Ready to sign your PDF? Try SigPDF free →

Frequently Asked Questions

Can I sign a PDF on my phone without downloading an app?

Yes. SigPDF runs entirely in your phone's web browser — there is nothing to download or install. Open the website, upload your PDF, add your signature, and download the signed version. It works on Safari (iPhone), Chrome (Android), and any other mobile browser.

Will a signature made on my phone be legally valid?

Yes. A signature created on your phone — whether drawn with your finger, typed, or uploaded as an image — is a legally valid electronic signature under the ESIGN Act, UETA, eIDAS, and similar laws in most countries. The device you use to create the signature does not affect its legal standing.

How do I sign a PDF from an email on my phone?

On iPhone, you can tap the PDF attachment in Mail to preview it, then use the Markup tool to sign it directly. On any phone, you can save the attachment to your device, open sigpdf.com in your browser, upload the saved PDF, sign it, and then attach the signed version to your reply email.

Is it safe to sign sensitive documents on my phone?

It can be, depending on the tool you use. With SigPDF, your document is processed entirely in your phone's browser and never uploaded to any server. This makes it safe for sensitive documents like contracts, financial forms, and medical authorizations. Avoid tools that upload your files to remote servers, especially on public Wi-Fi networks.