Using the strikethrough tool
Type on the left. The struck text appears on the right, and Line moves the stroke through the middle, under the text, over it, or sets it at a diagonal across each character.
The line runs through spaces too, so a struck sentence reads as one crossed-out block rather than a row of crossed-out words. Swap the boxes to take the line off again.
One mark per character
Each character gets a combining mark placed immediately after it. U+0336 is COMBINING LONG STROKE OVERLAY, and a renderer draws it across the character in front, which is why the stroke inherits that character's width rather than a width of its own. Underline is U+0332. Overline is U+0305, and the diagonal is U+0337.
That means a struck sentence is twice as long as it looks. Ten visible letters cost 20 code points, and a field with a 280-character limit will count all 20.
It also means the effect travels. Markdown's ~~tildes~~ only work where something parses markdown, and HTML needs a renderer that allows tags. A combining mark is text, so it goes into a spreadsheet cell, a filename or a push notification unchanged.
Where the line sits is the renderer's decision
Unicode says what a character means and stays out of how it looks. The standard describes U+0336 as a long stroke overlay and leaves the thickness, the length and the vertical position to whoever draws it.
So the same string looks different across platforms. A font with narrow glyphs leaves visible gaps between the strokes and the line breaks into dashes, while emoji and CJK characters run wider than the stroke, so the mark crosses part of the character and stops short. Test it where you plan to paste it.
There's a practical limit worth knowing. Some renderers reorder or drop combining marks during Unicode normalisation, and a form that runs NFC on your input may hand back text with the line gone.
Related conversions
Zalgo is this mechanism without the restraint, stacking up to 15 marks per character instead of one. Superscript swaps the character outright rather than decorating it, so the result is half the length.
Paste anything here into the Unicode converter to see the marks as code points.
Questions
How do I cross out text without markdown?
Type it above and copy the result. Each character carries its own combining stroke, so the line survives anywhere plain text does.
Why does the strikethrough look broken in some apps?
The font decides how long the stroke is. Narrow glyphs leave gaps between one character's stroke and the next, so the line reads as a dashed one.
Does struck-through text count as more characters?
Yes. Every visible character costs two code points, so a 100-character message becomes 200 against most limits.
Can I remove the strikethrough?
Paste it above and swap the boxes. All four marks this tool adds are stripped, along with any it finds from elsewhere.