Web & Encoding

URL Encoding Spaces: %20 vs + Explained

%20 is a percent-encoded space. A plus sign is decoded as a space only in form-style query serialization contexts, not universally across every URL component.

Published Aug 24, 2026

The short answer: %20 and + are not interchangeable everywhere

Percent encoding defines %20 for the space byte. Plus-as-space belongs to form/query serialization rules.

Spaces in URL paths

Use %20 for a space. A literal + in a path can remain a plus depending on the parser and application contract.

Spaces in query/form values

application/x-www-form-urlencoded serialization converts spaces to + and decodes + back to spaces within form-style values.

How to encode a literal plus sign

Use %2B when a plus must survive form-style query decoding as the + character.

%20, + and %2B side by side

Text	Common decoded value	Context
%20	space	Percent encoding in path or query
+	space	Form-style query value
%2B	+	Literal plus in a form-style query value

Double encoding: %20 → %2520

Encoding the percent sign in %20 produces %2520. One decode yields %20; a second explicit decode yields the space.

UTF-8 and percent-encoded bytes

Non-ASCII characters are commonly converted to UTF-8 bytes and then percent-encoded byte by byte. Decode at the correct component boundary.

Common mistakes

Decoding a complete URL when only one component should be decoded.
Treating + as a space in every URL component.
Forgetting %2B for a literal plus in form data.
Repeatedly decoding without knowing the serialization layers.

Try the examples in URL Decoder

The tool exposes raw and decoded values; the guide supplies the path and form-query context.

Try the example

Decode %20 in path and query values

Percent-encoded spaces appear in both components of this URL.

https://example.com/a%20b?q=hello%20world

Expected result: The decoded representation contains spaces while the raw component values remain inspectable.

Try the example

Compare + with %2B in a query

Form-style parsing treats + as a space and %2B as a literal plus.

https://example.com/search?q=hello+world&tag=a%2Bb

Expected result: The query values expose hello world and a+b under form-style semantics.

Try the example

Inspect two encoding layers

The encoded percent sign reveals a second %20 layer.

hello%2520world

Expected result: One layer is hello%20world; a second explicit layer becomes hello world.

Inspect each component

Decode URL space examples

Compare path, query and double-encoding behavior locally.

Open in URL Decoder →