Text to Decimal Converter

How to convert text to decimal byte values

Type or paste text and the decimal value of each UTF-8 byte appears immediately, space separated. Everything runs locally, so the text never leaves the browser.

The values are bytes, always 0 to 255, which is what a byte array in any language holds. Non-ASCII characters produce several bytes each, so the count of numbers is the byte length rather than the character count.

• Type or paste the text, for example Hello.
• Read the decimal byte values, for example 72 101 108 108 111.
• Replace the spaces with commas to build an array literal.
• Count the values to get the exact byte size of the string.
• Press Copy result to take the numbers away.

Bytes, code units, and code points are three different numbers

This page prints bytes. That is not the same as the number you get from most language APIs, and the mismatch is the single most common reason two tools disagree about the same character. JavaScript charCodeAt returns UTF-16 code units, Python ord returns Unicode code points, and both of those can exceed 255. A byte never can.

For plain ASCII all three agree, which is why the difference goes unnoticed until an accent appears. The letter e with an acute accent has code point 233, a single UTF-16 code unit of 233, and two UTF-8 bytes of 195 and 169. All four numbers describe the same character; they just answer different questions. If you are sizing a buffer, writing a file, or checking a length limit measured in bytes, the byte values on this page are the ones that matter.

• UTF-8 byte (this page): always 0 to 255, one or more per character.
• UTF-16 code unit (JavaScript charCodeAt): 0 to 65535, one or two per character.
• Unicode code point (Python ord): 0 to 1114111, exactly one per character.

Turning the output into a byte array

The values come out space separated because that is the neutral form, easy to read and trivially reshaped. Swap the spaces for ", " and wrap the result in brackets and you have a valid Python list, a JavaScript array, or a C initialiser: 72 101 108 108 111 becomes [72, 101, 108, 108, 111]. Every value is already inside the range an unsigned byte type expects, so no clamping is needed.

One language needs an extra step. Java and Kotlin bytes are signed, running from -128 to 127, so a value this page shows as 200 appears as -56 in a Java byte array. The bit pattern is identical and only the interpretation differs, so add 256 to any negative Java byte to recover the number printed here.