Golang length of map [2 Easy Methods]

Tuan Nguyen


In this tutorial we will explore different methods we can use to get length of map in golang.


Different methods to get golang length of map

Method-1: Use the len() function

map is an unordered collection of key-value pairs, where each key is unique. In Go programming, use the len() function and pass the map as an argument to get the length of a map.

In this example, we will learn how to use the len() function to get the length of a given map:

Syntax: The syntax to find the length of Map x is:

The function returns an integer indicating how many key-value pairs are in the map. In the following example, we'll count the items in the map studentRecord, where the student name is a key and the score is a value.

package main

import (

func main() {

	//initialize a map
	scoreRecord := map[string]float64{
		"Ariana": 8.6,
		"Bob":    9.3,
		"Clover": 7.8,
		"Daniel": 9,

	//calculate the length of the map
	mapLength := len(scoreRecord)

	//display the length
	fmt.Println("Map is:", scoreRecord)
	fmt.Println("Length of map :", mapLength)


Map is: map[Ariana:8.6 Bob:9.3 Clover:7.8 Daniel:9]
Length of map : 4


  • Firstly, declare and initialize the map, where the key is of data type string and value is of data type int.
  • Calculate the length of the map using thelen() length and pass the map as a parameter to it, then assign the returned length to mapLength.
  • Print out the map and the length mapLength of the map.


Method-2: Iterate over the map to count all elements in a nested map

We can use range statement to iterate over the map and count the number of elements in a nested map.

package main

import "fmt"

func main() {

	//initialize a nested map
	scoreRecord := map[string][]float64{
		"Ariana": []float64{5.3, 7.3, 6.9},
		"Bob":    []float64{8.3, 8.7, 9.2},
		"Clover": []float64{7.6, 9.2},
		"Daniel": []float64{8.8, 9.0, 8.9},

	//initialize a counter
	counter := 0
	for _, v := range scoreRecord {
		// add up the number of elements in nested map
		counter += len(v)

	fmt.Println("Number of elements in nested map is:", counter)


Number of elements in nested map is: 11



In this Golang Tutorial, we learned how to find the length of a Map, using two different methods:

  • Using len() function
  • Iterate over the map to count the elements



Golang for loop
Golang maps
Golang length of map


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Tuan Nguyen

He is proficient in Golang, Python, Java, MongoDB, Selenium, Spring Boot, Kubernetes, Scrapy, API development, Docker, Data Scraping, PrimeFaces, Linux, Data Structures, and Data Mining. With expertise spanning these technologies, he develops robust solutions and implements efficient data processing and management strategies across various projects and platforms. You can connect with him on LinkedIn.

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