ASCII to HTML Entities Converter

Validates strict 7-bit ASCII, then encodes every character, not just the HTML-significant five, as its decimal numeric character reference (&#N;), producing a fully reversible, character-for-character entity encoding rather than a security-focused escape. A free online tool from Staaarter, right in your browser.

Runs locallyUpdated 2026-07-27

Overview

Introduction

HTML numeric character references, H for the letter H, for example, let you represent any character by its decimal code point instead of the literal glyph.

This tool applies that encoding to every character of strict ASCII input, one entity per character, producing an output that's trivially reversible and useful for teaching or verifying exactly how character references map back to code points.

What Is ASCII to HTML Entities Converter?

A full-coverage numeric HTML entity encoder: unlike a typical HTML-escaping tool, it converts every character of the input, not just the five HTML-significant ones, into its &#N; decimal form.

It's built specifically for strict 7-bit ASCII input, rejecting anything above code point 127 rather than encoding it.

How ASCII to HTML Entities Converter Works

The input is validated character-by-character against the 0-127 ASCII range using this category's shared strict-ASCII validator.

If every character passes, each one's code point is wrapped in &#...; and the results are concatenated in order, with no separator needed since each entity is self-delimited by its trailing semicolon.

When To Use ASCII to HTML Entities Converter

Use it to demonstrate or verify how HTML numeric character references map to ASCII code points, or to produce a fully entity-encoded version of a short ASCII string for teaching purposes.

For actually making untrusted or dynamic text safe to embed in HTML, use HTML Entity Encoder instead, since escaping every character here is unnecessary overhead and not what that use case needs.

Features

Advantages

  • Fully reversible, character-for-character, with no special-casing required to decode correctly.
  • Guarantees the source text was pure 7-bit ASCII, since anything else is rejected up front.
  • Every character in the output is valid, renderable HTML on its own.

Limitations

  • Not a security escape: it doesn't selectively target the HTML-significant characters the way HTML Entity Encoder does, and using it for that purpose is needless overkill.
  • Rejects any input above code point 127; there's no fallback for accented or international text.

Examples

Encoding a short word

Input

Hi

Output

Hi

Each letter's ASCII code point (H=72, i=105) becomes its own decimal numeric entity, concatenated with no separator.

Encoding text with a space and punctuation

Input

Hi!

Output

Hi!

Every character, including punctuation, gets the same &#N; treatment, unlike a selective escaper that would leave ! untouched.

Rejecting a non-ASCII character

Input

café

Output

Character "é" at position 4 has code point 233 (0xE9), which is outside the 7-bit ASCII range (0-127).

Encoding is rejected outright rather than producing a numeric entity for a code point outside the guaranteed ASCII range.

Best Practices & Notes

Best Practices

  • Reach for HTML Entity Encoder instead if your goal is making user-supplied text safe to embed in a page; this tool's full-character encoding is unnecessary for that.
  • Use HTML Entities to ASCII Converter to verify a round trip back to your original text.

Developer Notes

Validation reuses the category's shared validateStrictAscii helper (which also returns the code-point-split character array), then each character's codePointAt(0) is wrapped in a template literal as &#${code};, joined with no separator since the trailing semicolon of each entity already delimits it.

ASCII to HTML Entities Converter Use Cases

  • Teaching or demonstrating how HTML numeric character references map to ASCII code points
  • Producing a fully entity-encoded ASCII string for round-trip testing of entity-decoding logic
  • Verifying exactly which code point a specific character corresponds to

Common Mistakes

  • Using this tool where HTML Entity Encoder is actually needed; encoding every character is unnecessary and produces much longer output than escaping just the five significant characters.
  • Assuming this handles non-ASCII text; it deliberately rejects anything above code point 127.

Tips

  • Count the semicolons in the output as a quick sanity check: there should be exactly as many &#...; groups as input characters.
  • Pair with HTML Entities to ASCII Converter to confirm the encoding round-trips back to your exact original text.

References

Frequently Asked Questions