What Is Height of Binary Tree in Data Structure?


Heather Bennett

In data structure, a binary tree is a hierarchical data structure in which each node has at most two children, referred to as the left child and the right child. The height of a binary tree is an important metric that measures the maximum number of edges between the root and any leaf node in the tree. It provides valuable insights into the efficiency and performance of various operations on the tree.

Understanding Binary Trees

A binary tree consists of nodes, where each node contains a key/value and pointers to its left and right children. The topmost node in the tree is called the root, while nodes with no children are referred to as leaf nodes. It’s worth noting that a binary tree can be empty, meaning it doesn’t contain any nodes.

To visualize a binary tree, imagine an inverted tree structure with the root at the top and subsequent levels branching downward. Each level of the tree represents a generation of nodes, starting with level 0 for the root and increasing as we move down.

Calculating Height of Binary Tree

The height of a binary tree can be determined using different algorithms, including recursive and iterative approaches. Here, we’ll focus on calculating it recursively.

To calculate the height of a binary tree:

  • Step 1: If the binary tree is empty (i.e., it doesn’t have any nodes), its height is 0. Return 0.
  • Step 2: If there’s only one node in the binary tree (i., it has no children), its height is 1. Return 1.
  • Step 3: If there are more than one node in the binary tree (i., it has children), recursively calculate the heights of the left and right subtrees.
  • Step 4: The height of the binary tree is the maximum height between the left and right subtrees, plus 1 (to account for the root node).

Let’s represent this algorithm in code:

<!-- Assuming a helper function 'getHeight' that calculates height recursively -->
function getHeight(node) {
  // Step 1
  if (node === null) {
    return 0;
  // Step 2
  if (node.left === null && node.right === null) {
    return 1;
  // Step 3
  let leftHeight = getHeight(node.left);
  let rightHeight = getHeight(node.right);
  // Step 4
  return Math.max(leftHeight, rightHeight) + 1;

By calling the ‘getHeight’ function on the root node of a binary tree, you can obtain its height.

Importance of Binary Tree Height

The height of a binary tree has several implications:

  • Efficiency of operations: The height affects the efficiency of various operations on a binary tree, such as insertion, deletion, searching, and balancing. In general, shorter trees tend to offer faster access times.
  • Determining tree type: Based on the height, we can classify a binary tree as balanced or unbalanced. Balanced trees have minimal differences in height between left and right subtrees, while unbalanced trees exhibit significant differences.
  • Maintaining balance: By keeping the height balanced, we can ensure that the tree remains efficient and doesn’t degenerate into a linked list-like structure, where the time complexity of operations worsens.


The height of a binary tree measures the maximum number of edges between the root and any leaf node. It’s an essential metric for evaluating the efficiency and performance of binary trees. By understanding how to calculate the height and its implications, you can effectively analyze, optimize, and maintain binary trees in your data structures.

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