How To Underline Text On iPhone

You tap, you type, you hunt for the underline button… and it’s nowhere. If you’ve ever tried to underline text on an iPhone 13 only to discover that some apps make it easy while others pretend the feature doesn’t exist, you’re not alone. On iOS, underline is not a universal, system-wide formatting switch. It’s app-dependent: some apps include full rich-text controls, others only allow bold/italic, and a few use plain text with no formatting at all.

This step-by-step guide shows you every practical way to add an underline on your iPhone 13 in 2025. You’ll learn exactly where it’s supported (Mail, Notes, Pages, Microsoft Word, Google Docs, Telegram), how to handle apps that don’t support underline (Messages/iMessage, WhatsApp, many social apps), and reliable workarounds (Unicode combining underlines, Shortcuts, and copy-paste tricks). We’ll also cover troubleshooting, best practices for readability, and FAQs so you can underline with confidence—without wasting time tapping through menus that won’t help.

Underline on iPhone 13: What You Need to Know Before You Start

• There’s no global underline toggle in iOS. You can’t flip a system switch and have underline work in every app.
  
• Underline depends on the app. If an app supports rich text, you’ll find underline in its formatting toolbar; if not, you need a workaround.
  
• Not all text fields are equal. A Notes title, an email body, and a Messages text box can look similar but behave very differently under the hood.
  
• iPhone 13 on iOS 17/18: Your device can run the latest iOS versions where Apple refined the formatting bars in Notes and Mail—great news for underline, but still app-dependent.
  

A helpful mental model: think in layers. First, ask “Does this app support rich text here?” If yes, you’ll usually see a formatting bar (often the Aa or BIU options). If no, use a workaround (Unicode, Shortcuts, or write in a rich-text app and paste into the destination).

Where Underline Is Natively Supported (and Where It Isn’t)

• Supported (straightforward):
  Mail (email body), Notes (newer iOS), Pages, Microsoft Word, Google Docs, Telegram’s rich-text fields, many blogging or document apps.
  
• Partially supported / depends on the spot:
  Some third-party note apps, some web editors in Safari (if they load a rich-text editor like TinyMCE/Quill). You’ll see a toolbar with an underline button or a formatting menu.
  
• Not supported natively (use workarounds):
  Messages/iMessage, WhatsApp, Instagram and X/Twitter composers, many plain-text fields.
  

If you don’t see a formatting bar or the underline icon (a U with a line under it), the field is likely plain text.

Method 1 — Underline in the Mail App (fast and reliable)

Great for: professional emails, resumes, agendas, detailed messages.

Steps:

1. Open Mail and start a New Message (or reply).
2. Type your text as usual.
3. Select the word or phrase you want to underline.
   • Press and hold on a word → adjust the selection handles.
4. On the editing bar just above the keyboard, tap the BIU or format button (the exact icon can appear as Aa or a formatting palette, depending on iOS version).
5. Tap Underline.
6. Continue composing. You can combine underline with bold and italic as needed.
   

Pro tips:

• Keep underline for emphasis or section labels. If you underline everything, nothing stands out.
• Avoid underlining text that’s also a link; on mobile, underlined non-links can confuse readers.
  

Method 2 — Underline in Notes (iOS 17/18 formatting bar)

Great for: school notes, planning lists, quick outlines, writing drafts.

Steps:

1. Open Notes and create or open a note.
2. Select the text to underline.
3. Tap the formatting bar (the Aa icon above the keyboard).
4. Choose Underline from the text styles.
5. Keep writing; the underline applies to the selected range. Tap Underline again to toggle off.
   

Common hiccup: If you don’t see Underline, you might be in a title or checklist mode that exposes a limited toolbar. Convert the segment to Body or Text format first, then open the full formatting options.

Use case ideas:

• Headings like reading list, underlined to separate sections in a long study note.
• Underline key due dates for assignments or project milestones.
• Combine underline for headings and bold for crucial terms inside paragraphs to keep a clean hierarchy.
  

Method 3 — Underline in Pages (Apple’s word processor)

Great for: reports, essays, flyers, formal letters.

Steps:

1. Open Pages and your document.
2. Select text.
3. Tap the paintbrush (Format) icon at the top.
4. Under Style (or Text → Style), choose Underline.
5. Pages lets you combine underline with fonts, spacing, and paragraph styles. Save your preferred style to reuse across documents.
   

Why use Pages? Pages feels “native” on iPhone, plays perfectly with iCloud, and offers predictable formatting when you later open the doc on a Mac or iPad.

Method 4 — Underline in Microsoft Word (iOS)

Great for: business documents, academic work, templates you’ll also open on Windows/Mac.

Steps:

1. Open Word and your document.
2. Select the text.
3. Tap the Home tab if needed to reveal the formatting ribbon.
4. Tap the U (Underline) icon.
5. You can also tap the U dropdown for underline styles (e.g., single, double, dotted) when available.
   

Power tip: If you use a Bluetooth keyboard with your iPhone, try Cmd + U to toggle underline (some keyboard/app combos support desktop-style shortcuts).

Method 5 — Underline in Google Docs (iOS & web)

Great for: collaboration, shared outlines, classroom assignments.

iOS app steps:

1. Open Google Docs and your file.
2. Select the text.
3. Tap the A icon with lines (Format).
4. In Text options, tap Underline.
   

Web in Safari (if you prefer):

• Open Docs in Safari → select text → use the toolbar U or menu path Format → Text → Underline.
  

Collaboration tip: If someone removes your underline when editing, check the document’s version history to restore your original styling if necessary.

Method 6 — Underline in Telegram (yes, it’s supported)

Great for: group announcements, formatted posts, channels.

Steps (typical Telegram on iOS):

1. In a chat, type your message.
2. Select the text to style.
3. Tap Formatting (A icon) if you see it, or choose Underline from the style pop-up.
   • If underline isn’t exposed, you can use Markdown/HTML bots or the client’s rich-text mode; many iOS builds include underline in the native picker.
     

Why Telegram works: Telegram supports rich text (bold, italic, underline, strikethrough, monospace) in many clients, making it friendlier than most messengers for precise formatting.

Method 7 — Messages/iMessage: why you can’t underline (and what to do instead)

Reality check: iMessage does not support underline natively. Apple keeps the Messages composer simple—emoji, stickers, effects, and Photos are front-and-center; text styling is not.

Workarounds:

1. Unicode “combining underline”
   
   • There’s a special character called combining low line (U+0332) that draws a line under the preceding character. Example: a̲ b̲ c̲
   • How to use: write your text elsewhere (Notes), then insert U+0332 after each character or use an online generator to apply the combining underline. Copy and paste the result into Messages.
   • Caveats: not every font aligns the line perfectly, some letters may look uneven, and screen readers can stutter. Use sparingly.
     
2. Create in a rich-text app, send as an image
   
   • Type and underline in Notes/Pages/Word, take a screenshot, and send the image.
   • Pros: perfect visual fidelity. Cons: not searchable, not accessible, can be awkward in long threads.
     
3. Emphasis alternatives
   
   • Use bold via a font app if you must (third-party keyboards), ALL CAPS (sparingly), or surround with underscores for faux-underline vibes like this (it won’t render as a real underline, but it can hint at emphasis).
     

Honesty corner: If you need consistent underlines in chat for work, apps like Telegram are a better fit than iMessage.

Method 8 — WhatsApp, Instagram, X/Twitter: underline limitations

• WhatsApp: supports bold (asterisks), italic (underscores), strikethrough (tildes), and monospace (backticks), but no underline. Use the Unicode combining underline trick or design your text image outside WhatsApp and send it.
  
• Instagram & X/Twitter: composers are mostly plain text. If you see underlined text in posts, it’s almost always a styled image. Some Unicode underlines paste, but alignment is inconsistent and can break across devices.
  
• Facebook posts: the web composer sometimes supports rich editors in groups or Pages via third-party tools, but on iPhone it’s usually plain text. Use images for assured styling.
  

If you need absolute control over text visuals on social, design in a graphics app (Canva, Pages export as image, Keynote) and post the image.

Method 9 — Use Unicode combining underline (the “universal” hack)

When native underline isn’t available, the combining low line character is the closest cross-app solution.

How to do it cleanly:

1. Draft your sentence in Notes.
2. For each character you want underlined, insert the combining underline: it’s typed after the character and renders a line beneath it.
3. Copy the entire underlined phrase and paste it in the destination app.
   

Pros:

• Works in many plain-text fields (Messages, WhatsApp, social captions).
  
• No special keyboard required if you copy/paste from a generator or a saved snippet.
  

Cons:

• Alignment can look jagged in some fonts.
  
• Accents and emoji don’t play nicely with combining underscores.
  
• Screen readers may read characters oddly (so be considerate in accessibility-critical contexts).
  

Practical tip: Save a ready-made underlined alphabet in a pinned note. Copy and paste letters as needed for short phrases like urgent, final, or approved.

Method 10 — Shortcuts that speed everything up

Apple’s Shortcuts app lets you automate common formatting tasks. While there’s no built-in “underline this selection everywhere” action, you can create helpful flows:

A) Make Rich Text → Underline → Copy

• Build a Shortcut that:
  
  1. Takes text from the Share Sheet or Clipboard,
  2. Converts to Rich Text,
  3. Applies Underline (via “Make Rich Text” and “Set Attributes” if available in your iOS version or by wrapping HTML like <u>your text</u> and converting),
  4. Copies the result back to the clipboard.
     
• Paste into Mail, Notes, or any app that accepts rich text. If the destination strips styling (iMessage), you’ll just see plain text—expected behavior.
  

B) HTML to rich text (for compatible apps)

• Shortcut: ask for text → wrap with <u>…</u> → convert HTML to rich text → copy.
  
• Paste into Mail/Notes/Docs; many will keep the underline.
  

C) Back Tap trigger

• Assign your underline Shortcut to Back Tap (Settings → Accessibility → Touch → Back Tap). Double-tap the back of your iPhone to run it on clipboard text and paste.
  

Shortcuts are great when you underline the same phrases repeatedly—for example, project phases or policy disclaimers—saving minutes every day.

Best practices: when to underline (and when not to)

• Use underline for structure, not decoration. Headlines, section labels, or a single pivotal sentence benefit; entire paragraphs don’t.
  
• Avoid underline on links’ neighbors. On mobile, underline strongly implies a link. If nearby text is also underlined, readers can tap the wrong thing.
  
• Pair underline with sparing bold. For a clean hierarchy: headings underlined, key words bold, never all at once everywhere.
  
• Mind accessibility. Screen readers will handle native underline just fine; they may struggle with Unicode combining underlines. If your audience depends on assistive tech, consider bold or clear headings instead.
  

Troubleshooting: if underline won’t appear or won’t stick

“There’s no underline button in this app.”
The field is likely plain text. Use Notes/Mail/Pages/Word to format, or use the Unicode combining underline trick. For long-term sanity, switch to an app that supports true rich text where you need it.

“I underlined in Notes, but when I pasted into Messages it disappeared.”
Messages strips most formatting. That’s expected. Send as an image, or use Unicode combining underline if you need the look.

“I pasted underlined text and it looks broken.”
You used Unicode combining underlines and the font isn’t aligning neatly. Try a shorter phrase, different characters, or switch to an image approach for pixel-perfect results.

“Google Docs/Word keeps undoing my underline after a collaborator edits.”
It happens in shared files. Re-apply underline and talk with collaborators about a simple style guide (e.g., keep headings underlined, avoid underline inside body paragraphs).

“My underline becomes a link in Mail.”
If the underlined text looks like a URL, Mail might auto-link it. Use a different phrase or apply underline to the words around the URL rather than the URL itself.

Real-world workflows (you can copy these)

A) Quick email emphasis (30 seconds)

• Write your email in Mail.
• Select the critical dates and actions → Underline.
• Optional: bold the verbs, underline the deadlines.
• Send. Clean, readable, unmistakable.
  

B) Lecture notes with structure

• In Notes, write headings like week 3: photosynthesis and underline the heading lines only.
  
• Bullet the details.
  
• Use bold for terms; leave body text plain. When you scan later, your eyes jump to the underlined headings first.
  

C) Social post where you must underline a single word

• Write in Notes.
  
• Apply Unicode combining underline to the one word you absolutely want underlined.
  
• Paste into Instagram/X. If it misaligns, screenshot your formatted note and post the image instead.
  

D) Cross-platform doc you’ll open on a PC later

• Draft in Google Docs or Word on iPhone.
  
• Underline headings with the toolbar.
  
• When you open the doc on desktop, your styling is there 1:1 with no surprises.
  

A brief aside on travel planning and readable itineraries

Formatting is about clarity and attention. If you’re preparing a shared note for a trip—flights, hotel confirmations, must-see spots—underline the section headers (dates, cities, confirmation numbers) and pair them with short bullet lists underneath. It keeps the whole plan scannable for everyone in the group. When the conversation shifts to timing, a thoughtful guide such as the Best time to visit Japan can anchor your plan in real seasons and festivals, while your underlined headings keep the itinerary tidy and easy to follow.

The Bottom Line

Underlining on iPhone 13 is easy when the app supports rich text—and frustrating when it doesn’t. The key is knowing which path to take:

• Use Mail, Notes, Pages, Word, Google Docs, Telegram for true underline with a visible formatting bar.
  
• For Messages, WhatsApp, and many social composers, rely on Unicode combining underlines for short emphasis or create a styled image for perfect, predictable results.
  
• If you underline frequently, save time with Shortcuts and keep a “snippets” note ready for copy-paste.
  

Once you adopt the right method for each context, underlining becomes second nature—quick, consistent, and clear—so your most important words get the attention they deserve without any extra fuss.

Frequently Asked Questions

Why can’t I underline text in Messages on iPhone 13?
Messages is a plain-text composer. Apple hasn’t added native underline (or bold/italic) there. You can paste text with Unicode combining underlines or send a formatted image, but Messages itself won’t format text.

Can I make underline work system-wide on iOS?
No. iOS doesn’t offer a global underline toggle. You need an app that supports rich text (Mail, Notes, Pages, Word, Docs) or a workaround for apps that don’t.

Is there a keyboard shortcut for underline on iPhone?
On the software keyboard, no. With a Bluetooth keyboard, some apps honor Cmd + U (like Word/Pages). Otherwise, tap the on-screen underline icon in each app’s toolbar.

How do I underline in WhatsApp on iPhone?
WhatsApp doesn’t support underline. It supports bold, italic, strikethrough, and monospace via simple characters. For underline, use Unicode combining underlines or send a styled image.

My underline button disappeared in Notes—why?
You may be editing a title, checklist, or a table cell with simplified formatting controls. Switch that line back to regular text/body, then open the formatting bar to reveal Underline.

My collaborator keeps removing underline in Google Docs.
Create a basic style guide (headings underlined, body plain) and ask collaborators to follow it. Use version history to restore formatting if needed.

Is underlining bad for accessibility?
Underlining itself is fine when used thoughtfully. Avoid underlining non-links that sit directly next to actual links. For screen-reader-heavy audiences, prefer bold or clear headings over Unicode combining underlines.

What’s the fastest path to underline an email subject?
Most email apps (including Mail) don’t style subject lines—they’re plain text by design. Put your emphasis in the first line of the email body and underline there instead.