Percent-encoding table

Every ASCII character that can need encoding in a URL, with its RFC 3986 class and whether encodeURIComponent, encodeURI and form encoding escape it. Letters A–Z, a–z and digits 0–9 never need encoding.

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Unreserved

A–Z a–z 0–9 - . _ ~

Never need encoding.

Reserved: gen-delims

: / ? # [ ] @

Split a URL into its parts.

Reserved: sub-delims

! $ & ' ( ) * + , ; =

Delimit data inside a part.

Everything else

space " % < > \ ^ ` { | }

Must always be encoded.

ASCII characters and their percent-encoding
Char	Name	Encoded	Dec	RFC 3986	encodeURIComponent	encodeURI	Form / URLSearchParams
NUL	Null	%00	0	control	%00	%00	%00
TAB	Horizontal tab	%09	9	control	%09	%09	%09
LF	Line feed	%0A	10	control	%0A	%0A	%0A
CR	Carriage return	%0D	13	control	%0D	%0D	%0D
SP	Space	%20	32	unsafe	%20	%20	+
!	Exclamation mark	%21	33	sub-delim	kept	kept	%21
"	Quotation mark	%22	34	unsafe	%22	%22	%22
#	Number sign (hash)	%23	35	gen-delim	%23	kept	%23
$	Dollar sign	%24	36	sub-delim	%24	kept	%24
%	Percent sign	%25	37	unsafe	%25	%25	%25
&	Ampersand	%26	38	sub-delim	%26	kept	%26
'	Apostrophe	%27	39	sub-delim	kept	kept	%27
(	Left parenthesis	%28	40	sub-delim	kept	kept	%28
)	Right parenthesis	%29	41	sub-delim	kept	kept	%29
*	Asterisk	%2A	42	sub-delim	kept	kept	kept
+	Plus sign	%2B	43	sub-delim	%2B	kept	%2B
,	Comma	%2C	44	sub-delim	%2C	kept	%2C
-	Hyphen-minus	%2D	45	unreserved	kept	kept	kept
.	Full stop	%2E	46	unreserved	kept	kept	kept
/	Solidus (slash)	%2F	47	gen-delim	%2F	kept	%2F
:	Colon	%3A	58	gen-delim	%3A	kept	%3A
;	Semicolon	%3B	59	sub-delim	%3B	kept	%3B
<	Less-than sign	%3C	60	unsafe	%3C	%3C	%3C
=	Equals sign	%3D	61	sub-delim	%3D	kept	%3D
>	Greater-than sign	%3E	62	unsafe	%3E	%3E	%3E
?	Question mark	%3F	63	gen-delim	%3F	kept	%3F
@	Commercial at	%40	64	gen-delim	%40	kept	%40
[	Left square bracket	%5B	91	gen-delim	%5B	%5B	%5B
\	Reverse solidus (backslash)	%5C	92	unsafe	%5C	%5C	%5C
]	Right square bracket	%5D	93	gen-delim	%5D	%5D	%5D
^	Circumflex accent	%5E	94	unsafe	%5E	%5E	%5E
_	Low line (underscore)	%5F	95	unreserved	kept	kept	kept
`	Grave accent (backtick)	%60	96	unsafe	%60	%60	%60
{	Left curly bracket	%7B	123	unsafe	%7B	%7B	%7B
\|	Vertical line (pipe)	%7C	124	unsafe	%7C	%7C	%7C
}	Right curly bracket	%7D	125	unsafe	%7D	%7D	%7D
~	Tilde	%7E	126	unreserved	kept	kept	%7E

Cells show each function's output for that character; “kept” means it is left as-is. Generated from the JavaScript engine's own functions and checked against RFC 3986 §2 and the WHATWG URL Standard. Free to reuse under CC BY 4.0 with a link back.

Non-ASCII characters become several bytes

URLs encode text as UTF-8 first, then percent-encode each byte. One character can therefore become two, three or four %XX groups. Paste any of these into the URL Decoder to see the bytes grouped back into characters.

éU+00E9

%C3%A9

Latin small letter e with acute · 2 bytes

üU+00FC

%C3%BC

Latin small letter u with diaeresis · 2 bytes

€U+20AC

%E2%82%AC

Euro sign · 3 bytes

日U+65E5

%E6%97%A5

CJK ideograph (sun, day) · 3 bytes

✓U+2713

%E2%9C%93

Check mark · 3 bytes

😀U+1F600

%F0%9F%98%80

Grinning face emoji · 4 bytes

Sources

Behaviour checked against RFC 3986, the WHATWG URL Standard and MDN. Updated October 3, 2026