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URL Encoder & Decoder (Percent Encoding)

Percent-encode special characters in URLs or decode URL-encoded query strings into plain text.

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About this URL Encoder & Decoder (Percent Encoding)

The URL Encoder & Decoder performs percent-encoding (RFC 3986) to escape reserved and unsafe characters in URL parameters and API query strings.

Transparent calculation methodology
Editorial review: CalculatorAll.online Editorial TeamLast reviewed: August 29, 2026

How this calculation works

The URL Encoder & Decoder performs percent-encoding (RFC 3986) to escape reserved and unsafe characters in URL parameters and API query strings.

Mathematical formula and logic

Replaces non-alphanumeric characters with '%' followed by their two-digit hexadecimal ASCII representation (e.g. space -> %20, & -> %26).

Worked example

'https://www.calculatorall.online/search?q=mortgage rate & loans=100%' encodes spaces to '%20' and '%' to '%25'.

Calculation assumptions

  • RFC 3986 Uniform Resource Identifier (URI) Generic Syntax compliance.
  • UTF-8 character percent-encoding.

Frequently asked questions

Why is URL encoding necessary?

URLs can only contain a limited set of ASCII characters. Characters like spaces, ampersands (&), question marks (?), and slashes (/) have special syntactic meaning and must be percent-encoded to prevent breaking URL parsing.

What is the difference between encodeURI and encodeURIComponent?

`encodeURI` preserves protocol and path delimiters like 'http://', '?', and '&', whereas `encodeURIComponent` encodes all characters including delimiters, making it suitable for query parameter values.

What does %20 mean in a URL?

`%20` is the percent-encoded representation of a space character (ASCII code 32 = 0x20 hex).

Can plus (+) be used instead of %20 for spaces?

In URL query parameter strings (application/x-www-form-urlencoded), '+' is traditionally used to represent spaces, whereas `%20` is universally valid across both path and query strings.

How are non-English characters encoded in URLs?

Non-ASCII characters (like accents, Cyrillic, or Chinese characters) are converted to their UTF-8 byte sequences and each byte is percent-encoded (e.g. 'é' becomes '%C3%A9').