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How to Optimize Your Images for SEO – A Guide on Image SEO

Hero image for image SEO optimization

Contents

Image optimization for SEO means improving your website’s images so they load quickly, look great, and help your site rank better on search engines like Google. Images are not just for decoration—they help explain your content, grab attention, and improve the user experience.

Do You Need Image Optimization for SEO?

When done correctly, image SEO can:

  • Make your website load faster, keeping visitors happy and reducing bounce rates.
  • Help search engines understand your images, increasing your chances of showing up in search results like Google Images or the image pack.
  • Improve accessibility for visually impaired users who rely on screen readers to understand your site.

Pro Tip: Faster-loading images are also critical for site speed, which is a ranking factor for Google.

Why Is Image Optimization Important?

Imagine visiting a site where the images are huge and take forever to load. Frustrating, right? That’s why optimizing images is important. It helps:

  • Speed Up Your Website: Large image files can slow down your site, hurting your ranking on search engines.
  • Improve User Experience: Visitors will stay longer if your images load quickly and look good.
  • Boost Your Search Rankings: Optimized images with proper alt text and file names make it easier for search engine crawlers to index them.

What You’ll Learn in This Guide

By the end of this guide, you’ll know:

  • How to choose the right image format for speed and quality.
  • The best way to resize and compress your image files for fast loading.
  • Why adding descriptive alt text is essential for image SEO.
  • How to use techniques like lazy loading to make your site even faster.

This article will help you answer questions like:

  • What image format is best for SEO?
  • How do I optimize my images to rank better in Google Images?
  • What is the ideal image resolution and size for SEO?

Let’s start with the details so you can start optimizing images on your site today to boost SEO!

The 3 Key Elements of Image Optimization for SEO

The basics of image optimization are basically three elements which are the most important ones.

1. Image Size

Image size refers to the dimensions of an image, such as width and height, measured in pixels. Large images that are bigger than the space they occupy on your website can slow down your page.

Why It Matters
Large images take longer to load, which can hurt your site speed and ranking on search engines. A smaller image that fits your website’s layout is faster and just as effective visually.

Best Practices for Image Size
Resize images to match their display size on your website. For full-width images, aim for a width of 1200px. Smaller elements like thumbnails can be 300px or less. Use tools like Adobe Photoshop, GIMP, or free online tools like TinyPNG to resize images.

Pro Tip: Always test your images on different devices to ensure they look good and load fast. This is important for creating responsive images that adapt to the user’s screen size.

2. Image Format

Choosing the right image format is crucial for balancing quality and file size. The format determines how the image is saved and displayed, which affects loading speed and visual appearance.

Common Image Formats for SEO

  • JPEG: Best for detailed images like photos. Smaller file sizes but slightly lower quality.
  • PNG: Good for images that need transparency, but larger in size.
  • WebP: A modern format offering the best compression without sacrificing quality. Recommended for web use.
  • SVG: Perfect for icons and simple graphics. Scales without losing quality.

Best Practices for Image Formats
Use JPEG or WebP for most images to reduce file size. Convert large PNG files to WebP whenever possible. Use SVG for logos and icons to keep them sharp on all devices.

Pro Tip: Test your images in different formats using tools like Squoosh to find the best balance between quality and size.

3. Image File Size

The file size of an image refers to the amount of space it takes on your server, measured in kilobytes (KB) or megabytes (MB). Large file sizes slow down your site, leading to a poor user experience and lower rankings.

How to Reduce File Size
Compress images using tools like TinyPNG, Squoosh, or Imagify. Save images in the smallest format possible without compromising image quality. Limit file sizes to under 500KB whenever possible.

Example
Original File: 3MB PNG
Compressed File: 300KB WebP (faster loading, same visual quality)

Pro Tip: If you use WordPress, install a plugin like Smush or Imagify to automatically compress images as you upload them.

Lazy Loading: Speeding Up Image Loading

Lazy loading is a technique that delays the loading of images until they are visible on the user’s screen. Instead of loading all images on a page immediately, lazy loading ensures that only the images currently in the user’s viewport (the visible part of their screen) are loaded first.

This approach helps improve site speed, especially on pages with many images, like blogs, e-commerce galleries, or portfolios.

Why Is Lazy Loading Important?

  • Improves Page Speed: Loading fewer images at first reduces initial load time, which is a ranking factor for search engines.
  • Enhances User Experience: Visitors see the content faster, even on slower connections.
  • Saves Resources: Reduces bandwidth usage, which is especially useful for mobile users.

How to Implement Lazy Loading

  1. HTML Attribute: Add loading=”lazy” to your image tags. This is supported by most modern browsers. Example:<img src="example.jpg" alt="Example Image" loading="lazy">
  2. Use WordPress Plugins: Tools like Lazy Load by WP Rocket can automatically enable lazy loading across your entire WordPress website. But also popular page builders like Elementor have a built in Lazy Load functionality.
  3. JavaScript Libraries: For advanced setups, consider libraries like lazysizes, which provide more customization options.

Pro Tip: WordPress users can enable lazy loading automatically through plugins, making it hassle-free to implement this feature site-wide while boosting WordPress SEO.

Showing how lazy loading works

Alt Text and Alt Tags: Enhancing SEO and Accessibility

Alt text (alternative text) is a description of an image, while an alt tag refers to the HTML attribute that contains the alt text. Both are used to:

  • Improve SEO: Help search engines understand the content of your images, boosting their visibility in Google Images.
  • Enhance Accessibility: Provide image descriptions for visually impaired users via screen readers.

Why They Matter

Alt text and tags are essential for image SEO and user accessibility. Missing or poorly written alt tags can mean lost traffic and a less inclusive website.

Examples of Good and Bad Alt Text

Lets take this image as an example:

chocolate chip cookies on a baking rack
  • Good Example: “Freshly baked chocolate chip cookies on a cooling rack.”
  • Why? It’s descriptive and provides context, helping both users and search engines.
  • Bad Example: “Cookies” or leaving it blank.
  • Why? It lacks detail and doesn’t help users or improve SEO.

Pro Tip: Always ensure every image on your site has a clear, descriptive alt text included in the alt tag.

For an in-depth guide on optimizing alt tags, visit our article on Alt Tags for SEO.

Image Quality: Balancing Clarity and Performance

High-quality images improve user experience by making your website visually appealing and professional. However, using low-quality images can harm your credibility, while overly large high-quality images can slow down your website. Finding the balance between clarity and performance is key.

Best Practices for Image Quality

  • Start with High-Quality Images: Use sharp, clear visuals that look professional.
  • Avoid Over-Compression: Compress images to reduce file size, but don’t sacrifice too much image quality.
  • Use the Right Resolution: For web use, 72 DPI (dots per inch) is typically enough. Higher DPI is unnecessary and increases file size without improving clarity for screens.

Online Tools for Optimizing Image Quality

  • iloveimg.com/resize-image: Quickly resize images to fit your website’s layout.
  • TinyPNG: Compress images while maintaining their quality.
  • Squoosh: Adjust resolution and file size directly in your browser.

Example

  • Before Optimization: A 3000×2000-pixel image at 5MB with too much resolution for web use.
  • After Optimization: A resized 1200×800-pixel image at 200KB, still sharp but much faster to load.
Image quality before and after

Pro Tip: Test your optimized images on mobile devices to ensure they remain crisp and clear on smaller screens.

Image File Names: Boosting SEO with Descriptive Labels

An image file name is not just a label for your image—it’s a chance to help search engines understand your content. A descriptive, keyword-rich file name can improve your image SEO and make it easier for your images to rank in Google Images so make sure to optimize image file names before using them.

Best Practices for Image File Names

  • Be Descriptive: Use clear and specific file names that describe the image’s content.Red Sneakers on a track
    • Example: Instead of “IMG1234.jpg,” use “red-sneakers-running-track.jpg.”
  • Include Keywords Naturally: Incorporate relevant keywords, but avoid keyword stuffing.Apples on a wooden table
    • Example: “organic-apples-on-wooden-table.jpg” instead of “apples-fruit-organic-keyword.jpg.”
  • Use Hyphens to Separate Words: Hyphens (-) are better than underscores (_) for readability by search engines.
    • Correct: “blue-widgets-on-display.jpg”
    • Incorrect: “blue_widgets_on_display.jpg”

The Impact of Poor File Names

Using generic names like “IMG001.jpg” doesn’t help search engines or users. Instead, descriptive file names can improve visibility in search results and make your website more organized.

Pro Tip: Always rename your images with meaningful file names as part of your image optimization workflow.

Image Sitemaps: Helping Search Engines Find Your Images

An image sitemap is a file that provides search engines with a list of all the images on your website. It ensures that your images are indexed properly, especially if they are loaded dynamically (e.g., through JavaScript) or are not directly linked in your website’s HTML.

Why Image Sitemaps Matter

  • Improved Indexing: Ensures all your images, including those not easily discoverable, are indexed by search engines like Google.
  • Enhanced Visibility: Helps your images appear in Google Images and other search results, increasing your site’s traffic.
  • Better SEO for Dynamic Content: If your site uses features like lazy loading or JavaScript to load images, a sitemap ensures those images are still indexed.

How to Create an Image Sitemap

  1. Automatically with Plugins:
  2. Manually:
    • Create an XML sitemap file and list your image URLs using the <image:image> tag. Example:<url> <loc>https://yourwebsite.com/example-page/</loc> <image:image> <image:loc>https://yourwebsite.com/images/example.jpg</image:loc> <image:title>Example Image Title</image:title> </image:image> </url>
  3. Use Online Tools:
    • Use free tools like XML-Sitemaps.com to generate an image sitemap for your site.

Submitting Your Image Sitemap

  • Go to Google Search Console.
  • Select your property and navigate to Sitemaps.
  • Add the URL of your sitemap (e.g., https://yourwebsite.com/sitemap_images.xml).

Pro Tip: Regularly update your image sitemap whenever you add new images to ensure they are indexed by search engines.

Screenshot of the google search console with highlighted Sitemap inputs

Responsive Images: Ensuring a Great User Experience Across Devices

Responsive images are images that automatically adjust their size and resolution to fit the user’s viewport or screen size. This ensures that your website looks great on all devices, including desktops, tablets, and smartphones while also optimizing the image size for each viewport.

Why Responsive Images Matter

  • Faster Load Times: Smaller devices load appropriately sized images, reducing file size and improving site speed.
  • Better User Experience: Images that adapt to screen sizes prevent issues like cropping or distortion.
  • Improved SEO: Search engines prioritize mobile-friendly websites, and responsive images contribute to mobile optimization.

How to Implement Responsive Images

  1. Use the HTML <picture> Element:
    This tag allows you to specify different image files for different screen sizes. Example:<picture> <source srcset="image-small.jpg" media="(max-width: 600px)"> <source srcset="image-large.jpg" media="(min-width: 601px)"> <img src="image-default.jpg" alt="Example Image"> </picture>
  2. Set Image Dimensions in CSS:
    Use CSS to ensure images scale properly. Example:img { max-width: 100%; height: auto; }
  3. Use Plugins or Tools for Automation:
    For WordPress sites, plugins like Smush or Imagify can help serve responsive images automatically.

Testing Your Responsive Images

Use tools like Google’s Mobile-Friendly Test to check how well your images perform on various devices.

Example Scenario

Imagine a 1920×1080-pixel image.

  • On desktop: The full image is displayed.
  • On mobile: A smaller version (e.g., 600×400 pixels) is loaded to save bandwidth and ensure it fits the screen properly.

Pro Tip: Always test your site on multiple devices to ensure your images are scaling correctly and maintaining quality.

Conclusion: Optimizing Images for Better SEO and User Experience

Images play a crucial role in both SEO and user experience. Properly optimized images improve site speed, make your content more accessible, and help your website rank higher in search results, including Google Images. By following the steps in this guide, you can ensure your images enhance your website’s performance without slowing it down.

Key Takeaways

  • Image Size and Format: Resize images and use efficient formats like WebP to balance quality and speed.
  • Lazy Loading: Implement lazy loading to improve site speed, especially for image-heavy pages.
  • Alt Text and File Names: Use descriptive alt text and file names to help search engines and users understand your images.
  • Responsive Images: Ensure your images look great on all devices for better mobile optimization.
  • Image Sitemaps: Use a sitemap to help search engines index all your images properly.

Next Steps

  1. Audit your current images using tools like Google PageSpeed Insights or GTmetrix.
  2. Start optimizing your images with online tools like TinyPNG or iloveimg.
  3. Implement responsive and lazy loading techniques on your site.

Pro Tip: Regularly check your website for missing alt text and large, unoptimized images. Keeping your images optimized is an ongoing process that contributes to better image seo and user satisfaction.

Picture of Jonas Lindemann

Jonas Lindemann

I’m an experienced SEO professional with over a decade of helping over 100 businesses rank higher online, especially local businesses, e-commerce stores and SaaS. As the co-founder of LPagery, I specialize in practical, proven strategies for regular SEO and Local SEO success.

About The Author

Picture of Jonas Lindemann

Jonas Lindemann

I’m an experienced SEO professional with over a decade of helping businesses rank higher online, especially local businesses, e-commerce stores and SaaS. As the co-founder of LPagery, I specialize in practical, proven strategies for regular SEO and Local SEO success.

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