Why its important to optimise image sizes on websites

Why its important to optimise image sizes on websites

Why its important to optimise image sizes on websites

As a responsible website designer or owner, understanding how image dimensions, file formats, and compression affect your site’s speed and user experience is crucial. In this comprehensive guide, we will cover everything you need to know:

Why Care About Website Image Sizes & Performance?

1. User Expectations and SEO:

People expect websites to load quickly, and search engines like Google prioritize fast-loading sites. Slow page load times can lead to visitor disinterest and higher bounce rates.

2. Mobile Traffic:

With approximately half of your visitors using mobile devices, delivering optimal image sizes is critical. Failure to do so can result in decreased traffic and lower Google rankings.

3. Website Performance Metrics:

Tools like Google PageSpeed Insights, GTMetrix, and Page Weight by imgIX help identify image-related performance issues. Common problems include oversized images and slow loading times.

Optimizing Images for Web Performance

The primary goal of image optimization is to reduce file sizes while maintaining acceptable quality. Smaller files lead to faster page loads and better user experiences. Let’s explore the three main guidelines for achieving this:

1. Best Image Sizes for Websites (Dimensions in Pixels)

Start by determining the right image dimensions for your pages. Consider the following:

  • Homepage Banners: Around 1920 x 1080 pixels for desktop displays.
  • Blog Post Images: Typically 1200 x 800 pixels or similar.
  • Thumbnail Images: Smaller dimensions, such as 300 x 200 pixels.

Remember that responsive designs adapt to various screen sizes, so consider multiple breakpoints.

2. File Formats: JPEG, PNG, and WebP

  • JPEG: Ideal for photographs and images with gradients. Use JPEG for high-quality visuals while keeping file sizes manageable.
  • PNG: Suitable for images with transparency (e.g., logos). PNG-8 for simple graphics, and PNG-24 for more complex ones.
  • WebP: A modern format that offers excellent compression and quality. Use it if browser support allows.

3. Compression Techniques

  • Lossless Compression: Reduces file size without sacrificing quality. Suitable for icons, logos, and graphics.
  • Lossy Compression: Sacrifices some quality but significantly reduces file size. Ideal for photographs.

Testing Your Site’s Speed

Use tools like Google PageSpeed Insights to identify performance bottlenecks related to images. Address issues such as:

  • Serve Scaled Images: Ensure images are appropriately sized for their display context.
  • Optimize Images: Compress images without compromising quality.
  • Leverage Browser Caching: Set appropriate cache expiration headers for images.


Optimizing website images is a balancing act between visual impact and performance. By following these guidelines, you’ll create a better user experience, improve page speed, and enhance your site’s overall performance. Remember, every kilobyte adds on to your site’s load speed.

Do you need assistance optimizing your website? Get in touch with us! We are ready and willing to assist in boosting your website’s performance.

Related Posts