Infinity symbol (∞) in HTML
The infinity symbol is the sideways figure eight, formally a lemniscate. Its named reference is ∞ and its code point is U+221E.
At a glance
- Character
- ∞
- Named entity
- ∞
- Decimal reference
- ∞
- Hex reference
- ∞
- Unicode code point
- U+221E
- Unicode name
- INFINITY
- In the entity reference
- Math, and pinned in quick access
In detail
In mathematics the symbol is not a number. It names a limit or an unbounded end of an interval, which is why an expression treating it as a quantity to be added or divided is meaningless. That distinction survives into software: a floating point positive infinity behaves like a value in arithmetic, and the results it produces for operations like infinity minus infinity are defined as not a number precisely because the mathematics has no answer.
On the web its commonest job is a pricing table, standing for unlimited. It works because it is instantly readable, and it fails because it is only readable to someone who can see it. A screen reader may say infinity, may say nothing, or may describe the glyph, none of which tells a listener that a plan includes unlimited projects. The word belongs in the accessible name whatever the glyph does.
Two neighbours cause trouble. Proportional to at U+221D is drawn with a similar open loop and states a completely different relation. The permanent paper sign at U+267E is a circled infinity used in publishing to mark acid free stock, and there is an emoji built on that circled character which renders in colour on many platforms and will not inherit your text colour.
As an interval bound it takes a sign. Negative infinity is written with a minus in front, using the real minus sign rather than a hyphen for the same alignment reasons as any other negative value, and the bracket beside it is always the exclusive round one because the bound is never attained.
Examples
<td>
<span aria-hidden="true">∞</span>
<span class="sr-only">Unlimited</span>
</td><p>The domain is (−∞, 0) ∪ (0, ∞).</p>Round brackets on both infinite ends, because the bound is never included.
Things that catch people out
- A glyph on its own in a pricing table is unreadable to anyone using a screen reader. Pair it with the word unlimited in visually hidden text.
- The symbol is not a number. Rendering a computed value that came back as floating point infinity usually means a division by zero upstream, not a legitimately unlimited quantity.
- The circled infinity at U+267E and the emoji built on it will not inherit your text colour, which breaks a monochrome table.
Try it: HTML Entity Reference
Search 152 entities across 9 categories, switch the copy format between the character, the name, the decimal form and the hex form, and copy in one click.
HTML Entity Reference
LOCAL · Browser-OnlySearchable reference of 150+ HTML entities with one-click copy in any format
152 entities across 9 categories
Commonly Used
→Arrows(13)
±Math(35)
$Currency(8)
…Punctuation(21)
©Symbols(24)
πGreek(30)
½Fractions(6)
●Geometric(7)
æLatin Special(8)
Click any entity card to copy it in your chosen format. All data is embedded in the page and works offline.
Related HTML entities
All html entities →Approximately equal to (≈) in HTML
The almost equal to sign at U+2248 with its entity forms, and how it differs from the congruent, asymptotic and identical to signs it is confused with.
Minus sign (−) in HTML
The true minus sign at U+2212 and the hyphen-minus at U+002D. Why negative numbers in a table need the real character, and where it breaks copy and paste.
Mathematical operator entities: sets, logic and calculus
Named entities for summation, integral, partial differential, set membership, union, intersection and the logical connectives, with their code points.
Per mille sign (‰) in HTML
The per mille sign at U+2030, its entity forms, where parts per thousand are the natural unit, and the per ten thousand character used for basis points.
Square root symbol (√) in HTML
The radical sign at U+221A, its entity forms, why it has no overbar, when parentheses are compulsory, and the cube and fourth root characters.
Fraction characters: one half, one quarter, three quarters
The vulgar fraction characters at U+00BC, U+00BD and U+00BE, their entity forms, the wider fraction block, and when a fraction slash is the better answer.
Tools for this
- HTML Entity Reference Free online HTML entity reference - search and copy HTML entities with live preview
- HTML Entity Encoder Free online HTML entity encoder - encode or decode HTML entities to prevent XSS and display issues