How to Set Browser Window Size in Selenium WebDriver

In Selenium WebDriver, you can set the browser window size using the driver.manage().window().setSize(new Dimension(width, height)) method. This lets you specify the exact width and height in pixels for the browser window.

Syntax

The syntax to set the browser window size in Selenium WebDriver involves creating a Dimension object with the desired width and height, then passing it to the setSize() method of the browser window.

• driver: Your WebDriver instance controlling the browser.
• manage(): Accesses browser management options.
• window(): Accesses the browser window controls.
• setSize(Dimension size): Sets the window size to the specified dimensions.
• Dimension(width, height): Represents the size in pixels.

java

driver.manage().window().setSize(new Dimension(1024, 768));

Example

This example shows how to open a Chrome browser using Selenium WebDriver, set the window size to 1024x768 pixels, and then close the browser.

java

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.Dimension;

public class SetWindowSizeExample {
    public static void main(String[] args) {
        // Set path to chromedriver executable if needed
        // System.setProperty("webdriver.chrome.driver", "/path/to/chromedriver");

        WebDriver driver = new ChromeDriver();

        // Set browser window size to 1024x768
        driver.manage().window().setSize(new Dimension(1024, 768));

        // Open a website
        driver.get("https://www.example.com");

        // Pause to see the window size effect (optional)
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        // Close the browser
        driver.quit();
    }
}

Output

Browser window opens at 1024x768 size, loads https://www.example.com, then closes after 3 seconds.

Common Pitfalls

Common mistakes when setting browser window size include:

• Not importing the Dimension class, causing compilation errors.
• Setting the size before initializing the WebDriver instance.
• Confusing setSize() with maximize() which maximizes the window instead of setting a custom size.
• Using incorrect units; Selenium expects pixels, not percentages or other units.

Always ensure the WebDriver is initialized before setting the window size.

java

/* Wrong way: setting size before driver initialization */
// driver.manage().window().setSize(new Dimension(800, 600));
// WebDriver driver = new ChromeDriver();

/* Right way: initialize driver first */
WebDriver driver = new ChromeDriver();
driver.manage().window().setSize(new Dimension(800, 600));

Quick Reference

Method	Description
driver.manage().window().setSize(new Dimension(width, height))	Sets the browser window size to specified width and height in pixels.
driver.manage().window().maximize()	Maximizes the browser window to full screen.
driver.manage().window().fullscreen()	Sets the browser window to full screen mode (like pressing F11).

Key Takeaways

Always initialize the WebDriver before setting the window size.

Use the Dimension class to specify width and height in pixels.

setSize() sets exact window size; maximize() fills the screen.

Import org.openqa.selenium.Dimension to avoid errors.

Setting window size helps test responsive layouts reliably.