How to Strikethrough in Slack: Shortcut, Tildes and Mobile

To strikethrough text in Slack, select it and press Cmd+Shift+X on a Mac or Ctrl+Shift+X on Windows and Linux. You can also type one tilde on each side of the words, like ~no longer true~, and Slack crosses them out. The Strikethrough button in the formatting toolbar does the same. On iPhone and Android, select the text, tap Aa, and choose strikethrough. It works the same in channels, direct messages, group DMs and threads. We tested the shortcut, the tildes and six tilde variants in the Slack web app on 4 October; the results are below.

Four ways to cross out text in Slack

With the shortcut. Type your message, select the words, and press Cmd+Shift+X or Ctrl+Shift+X. Press it again on the same text to remove the line. One trap from our test: if you press End after striking the last words and keep typing, the new words are struck too. In our first try, "3 pm to 4 pm" all came out crossed out. Press the shortcut once more before you type on.

With tildes. Type a tilde, the words, and a tilde, with no spaces between the tildes and the words. In the web app the line appears as soon as you type the closing tilde, and the tildes disappear from the message box. On a US keyboard the tilde is Shift plus the key left of 1. On an iPhone it is on the symbols page (tap 123, then #+=). On Android with Gboard, tap ?123 and look on the second symbols page.

With the toolbar. The formatting toolbar under the message field has a Strikethrough button between Underline and Code. If you do not see the toolbar, click the formatting icon (Aa) in the message field, or check whether you turned on markup in Preferences, Advanced.

How to cross out text on iPhone and Android

• Type your message in the Slack app.
• Select the words: double-tap a word, then drag the handles.
• Tap Aa above the keyboard to show the formatting options.
• Tap strikethrough, then send.

Typing tildes works on mobile too, if you find typing faster than tapping.

When to use strikethrough in Slack

Strikethrough is useful when the old text still matters:

• • Corrections that people should notice. "The review is at ~3 pm~ 4 pm." Editing the time silently can confuse someone who already read the first version, because Slack only adds a small (edited) label. More on that in does Slack show edited messages.
• • Checklists in a message. Cross out tasks as you finish them in a pinned message or a standup thread.
• • Changed plans. "Lunch at the ~Thai place~ pizza place" keeps the joke and the change.
• • Softer edits. A crossed-out word can be a light joke, the way people do in chat.

For a long checklist that many people update, a Slack list or canvas is a better tool. See Slack canvas vs lists.

Slack strikethrough not working

We sent each of these through Slack's chat.postMessage and read back how Slack stored them. Only two of six were crossed out:

• Two tildes. GitHub markdown uses ~~text~~. Slack left it as plain text with all four tildes showing, both in the message box and through the API. Use one tilde on each side.

• Spaces inside the tildes. ~ done ~ stays plain text. The tilde has to touch the first and last letter.

• Tildes inside a word. half~word~ stayed plain. To cross out part of a word, select it and use the shortcut.

• Inside code. Text in inline code or a code block shows the tildes as typed. See how to make a code block in Slack.

• Markup preference on. With Format messages with markup turned on in Preferences, Advanced, you see the tildes while typing, and the line appears only after you send.

If you paste a markdown document with two-tilde strikethrough, run it through the Markdown to Slack converter first; it rewrites the markup for Slack.

How to underline in Slack

Select the words in the message box and click Underline in the formatting toolbar, or press Cmd+U on a Mac. Underline has no typed marker: _text_ makes italics, and __text__ is not underline either. Slack's keyboard shortcuts page, read on 5 October, lists Underline selected text: Cmd+U in its Mac table. Its Windows and Linux table has bold (Ctrl+B), italics (Ctrl+I) and strikethrough (Ctrl+Shift+X), and no underline entry, so on Windows the toolbar button is the documented way.

We underlined a word with Cmd+U and sent it. Slack stored the style as "underline": true, but the plain-text version of the message, used in notifications and old integrations, was just "Underlined word" with no marker. Cmd+U also worked with Format messages with markup turned on (Preferences, Advanced) in our 28 September test, even though that mode hides the toolbar.

Underline does not work in three places:

• Bot and API messages. Slack's mrkdwn has *bold*, _italic_ and ~strike~, and no underline. We sent __u__ through chat.postMessage, and the underscores showed as typed.

• The Block Kit markdown block. Its list of supported markdown has no underline. In our test, __u__ in a markdown block came out bold.

• The phone apps. Slack's help gives no underline steps for iPhone or Android. Type the message on desktop if the underline matters.

Where you cannot underline, bold is the usual way to stress a word. Some sites make "underlined" text from Unicode combining characters, U+0332 after each letter. It shows a line in many fonts, but every letter now carries a hidden second character:

text = "deadline"
underlined = "".join(ch + "\u0332" for ch in text)
print(underlined)
print(len(text), len(underlined))

It prints d̲e̲a̲d̲l̲i̲n̲e̲ and 8 16. Screen readers read the extra characters, and a search for "deadline" in Slack may not find the message, so we do not use it in work messages. Superscript has the same gap: Slack has no format for it, and only pasted Unicode characters such as ² work, as our five test messages in Slack superscript show.

Strikethrough in Slack bot and API messages

In a message sent through the API, one tilde on each side works in any text that Slack reads as mrkdwn. In our test Slack turned ~one tilde~ into a rich text element with "style": {"strike": true}:

{
  "text": "Deploy checklist: ~run migrations~ ~build~ smoke test"
}

In Block Kit rich text, set the strike style on a text element:

{
  "type": "rich_text",
  "elements": [
    {
      "type": "rich_text_section",
      "elements": [
        { "type": "text", "text": "old price", "style": { "strike": true } },
        { "type": "text", "text": " new price" }
      ]
    }
  ]
}

A plain_text object never formats, so tildes show as they are. Bold, italic and the rest of the formatting keys are in how to bold text in Slack and our Slack keyboard shortcuts guide.

If the Strikethrough button is not there at all, see Slack formatting toolbar missing.

FAQ

What is the strikethrough shortcut in Slack? Cmd+Shift+X on Mac, Ctrl+Shift+X on Windows and Linux.

How do I remove strikethrough in Slack? Select the crossed-out text and press the shortcut again, or click the Strikethrough button.

Can I strikethrough a message I already sent? Yes. Edit the message, select the words, press the shortcut, and save.

Is there an underline shortcut on Windows? Not in Slack's shortcut list. Select the text and click Underline in the formatting toolbar.