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Unicode Text Segmentation for Go (or: How to Count Characters in a String)
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Unicode Text Segmentation for Go

Godoc Reference Go Report

This Go package implements Unicode Text Segmentation according to Unicode Standard Annex #29.

At this point, only the determination of grapheme cluster boundaries is implemented.


In Go, strings are read-only slices of bytes. They can be turned into Unicode code points using the for loop or by casting: []rune(str). However, multiple code points may be combined into one user-perceived character or what the Unicode specification calls "grapheme cluster". Here are some examples:

String Bytes (UTF-8) Code points (runes) Grapheme clusters
Käse 6 bytes: 4b 61 cc 88 73 65 5 code points: 4b 61 308 73 65 4 clusters: [4b],[61 308],[73],[65]
🏳️‍🌈 14 bytes: f0 9f 8f b3 ef b8 8f e2 80 8d f0 9f 8c 88 4 code points: 1f3f3 fe0f 200d 1f308 1 cluster: [1f3f3 fe0f 200d 1f308]
🇩🇪 8 bytes: f0 9f 87 a9 f0 9f 87 aa 2 code points: 1f1e9 1f1ea 1 cluster: [1f1e9 1f1ea]

This package provides a tool to iterate over these grapheme clusters. This may be used to determine the number of user-perceived characters, to split strings in their intended places, or to extract individual characters which form a unit.


go get

Basic Example

package uniseg

import (


func main() {
	gr := uniseg.NewGraphemes("👍🏼!")
	for gr.Next() {
		fmt.Printf("%x ", gr.Runes())
	// Output: [1f44d 1f3fc] [21]


Refer to for the package's documentation.


This package does not depend on any packages outside the standard library.

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