Images in SEO
Images play an important role in both user experience and search engine optimization. Properly optimized images help your website pages load faster, improve accessibility, and increase visibility in Google search results (both web and image search).
- Image SEO helps search engines understand what your images are about.
- Optimized images improve page speed, which directly impacts rankings and user experience.
- Image attributes like alternate text and file names improve accessibility for screen readers.
- Well optimized images can drive additional organic traffic from image search.
- Poorly optimized images slow down websites and weaken overall SEO performance.
What is Image SEO?
Image SEO is the practice of optimizing images so that search engines can easily understand, index, and rank them, while also ensuring the images load quickly and look great for users.
The practice of Image optimisation involves improving multiple elements such as image file names, alternate text, image file size, image dimensions, and image formats (JPEG, PNG, WebP, AVIF, SVG). When done correctly, image SEO optimisation helps boost page speed, improves accessibility, rankings, and visibility in both Google Search and Google Images.
Common areas that image SEO focuses on include:
- Descriptive file names that reflect what the image actually shows.
- Alternate text helps search engines and screen readers understand what the image is all about.
- Compression and proper sizing to reduce file weight and improve load times.
- Modern image formats to deliver high quality visuals with smaller file sizes.
- Context around images like captions and surrounding content to strengthen relevance.
Image SEO - Key Elements
Image File Names
Search engines primarily understand text, but not images and other files which aren't textual in nature. So to understand an image's content, search engines try to read the image file name.A descriptive name helps them understand what the image is about and improves your chances of ranking in image search.
Good: blue-running-shoes-men.jpg
Bad: IMG_4589.jpg
The first image is descriptive and tells search engine that the image is about running shoes for men and is blue in color. The second file name is generic and does not convey any meaning.
Alternate Text
Alternate text is added to the "alt" element of an image and it describes the content of the image for search engines and screen readers. It improves accessibility and provides context when an image can’t load.
Best practices:
- Clearly describe what the image is all about.
- Include keywords naturally, do not do keyword stuffing in alternate text.
- Keep it concise and meaningful.
Alt text is one of the strongest on-page signals for image SEO.
Image Size and Compression
Large images are one of the most common reasons webpages load slowly. Compression reduces file size so that the images load faster in the client side.
Compressed images help:
- Pages load faster
- Improves Core Web Vitals
- Reduce web server's bandwidth usage
- Enhances mobile performance
Image Formats
Choosing the right format affects both quality and speed. Different formats work best for different image types.
- JPEG – Best for photographs
- PNG – Best for transparent graphics
- WebP / AVIF – Modern formats with superior compression
- SVG – Best for icons and vector graphics
Using next-gen formats like WebP or AVIF can significantly reduce page weight.
Image Dimensions
Uploading images much larger than their display size wastes resources and slows down your page.
The best practice is to match image dimensions to the layout where the image will be shown, and avoid relying only on CSS to scale down oversized images.
Example of Good vs Bad Image SEO
Examples of Good Image SEO
| Example | Why this is good |
|---|---|
| organic-coffee-beans.jpg | Descriptive and relevant file name that helps search engines understand what the image shows. |
| Alternate text: Fresh organic coffee beans in a glass jar | Clear, natural description that improves accessibility and provides useful context. |
| Compressed to 150 KB | Smaller file sizes load faster, improve user experience, and support better Core Web Vitals. |
| Format: WebP | Modern format that keeps quality high while reducing file size compared to older formats. |
Examples of Bad Image SEO
| Example | Why this is bad |
|---|---|
| DSC_00987.jpg | Generic file name gives no context to users or search engines about what the image is. |
| Alternate text: coffee coffee beans best coffee cheap coffee | Keyword stuffing makes the content unreadable, untrustworthy, and may be treated as spam. |
| Image size: 4 MB | Overly large files slow down page load speed and negatively affect SEO and conversions. |
| Oversized image scaled down using CSS | The browser still downloads the full image, wasting bandwidth and slowing down performance. |
When optimizing images, aim for clarity, relevance, and speed. The goal is to help users and search engines understand the visuals while keeping your pages lightweight and fast.
FAQs
The file name provides an initial hint to search engines about the image's content. Descriptive names help in better indexing and relevance during searches.
No. It's best to stick to lowercase letters and hyphens. Avoid capitals and special characters for SEO-friendly and easy-to-parse URLs.
While there's no strict "limit," it's wise to keep it succinct. Typically, 125 characters or less should convey the image's essence without overwhelming screen readers.
Search engines use alt text to understand the content and context of an image, helping in indexing it appropriately for relevant search queries.