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Get the size of an image

Written byPhuoc Nguyen
Level 1 — Basic
21 Feb, 2020
Last updated
07 May, 2021

Image is already loaded

const image = document.querySelector(...);

// Get the original size
const naturalWidth = image.naturalWidth;
const naturalHeight = image.naturalHeight;

// Get the scaled size
const width = image.width;
const height = image.height;

Image is not loaded yet

Listen on the `load` event to calculate the size of image which can be loaded via a given URL:
const image = document.createElement('img');
image.addEventListener('load', function (e) {
// Get the size
const width = e.target.width;
const height = e.target.height;

// Set the source
image.src = '/path/to/image.png';
We can use a `Promise` to turn the snippet to a reusable function:
const calculateSize = function (url) {
return new Promise(function (resolve, reject) {
const image = document.createElement('img');
image.addEventListener('load', function (e) {
width: e.target.width,
height: e.target.height,

image.addEventListener('error', function () {

image.src = url;

calculateSize('/path/to/image.png').then(function (data) {
const width = data.width;
const height = data.height;

Use case

Assume that you want to show the size of avatar which can be uploaded via a file input:
<input type="file" id="avatar" />

<!-- Display the size -->
<div id="size" />
First, we need to get the selected file, and then load it via `FileReader`:
const avatarEle = document.getElementById('avatar');
const sizeEle = document.getElementById('size');

avatarEle.addEventListener('change', function (e) {
// Get the selected file
const file = e.target.files[0];

const reader = new FileReader();
reader.addEventListener('loadend', function (e) {
const src = e.target.result;

calculateSize(src).then(function (data) {
const width = data.width;
const height = data.height;

sizeEle.innerHTML = `${width} x ${height}`;

See also

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Phước Nguyễn