What Are the Different Image File Types? A Guide to Choosing and Optimising for SEO

Images play a huge role in how users experience your website. They grab attention, showcase your products, and help tell your brand story. But not all image file types are created equal. Choosing the right format, and optimising it for SEO, can make a big difference to your site’s speed, visibility, and user experience.

Common Image File Types

1. JPEG (or JPG)

Best for photographs and images with lots of colour. JPEGs offer good quality with relatively small file sizes, making them one of the most popular formats for websites.

2. PNG

Ideal for graphics, icons, or images requiring transparency. PNGs provide higher quality than JPEGs but usually come with larger file sizes.

3. GIF

Best for simple animations or very small graphics. GIFs are limited in colour range but are great for images such as very small icons.

4. SVG

Perfect for logos, icons, and line art. SVGs are scalable, meaning they look sharp at any size without losing quality, ideal for responsive web design.

5. WebP

A modern format created by Google that combines the best of JPEG and PNG: high quality with much smaller file sizes. Many browsers now support WebP, making it an excellent choice for website optimisation.

6. TIFF

Often used in print rather than web, as TIFF files are very large and preserve high image quality. Not recommended for websites due to slow load times.

Optimising Images for SEO

Choosing the right file type is only the first step. To maximise performance and search visibility, images should be optimised for SEO:

1. Use Descriptive File Names

Instead of uploading an image called IMG_1234.jpg, use keywords relevant to the content and product, such as outdoor-kitchen-bbq.jpg. This helps search engines understand what the image is about and improves your chance of showing up in image search results.

2. Keep File Sizes Small

Large images can slow down your website, leading to higher bounce rates and lower rankings. Compress your images before uploading using tools like TinyPNG or ImageOptim, and aim for the smallest possible file size without losing noticeable quality.

3. Choose the Right Format

• Use JPEGs for photos.
• Use PNGs for graphics or images with transparency.
• Consider WebP for smaller file sizes without sacrificing quality.
• Use SVGs for logos and icons.

4. Add Alt Text

Alt text describes an image to both search engines and users with screen readers. Write short, descriptive phrases that include relevant keywords where appropriate.

5. Responsive Images

Ensure your images scale properly across different devices. Responsive website design helps deliver the right size image for mobile, tablet, and desktop, improving both performance and user experience.

Final Thoughts

Understanding the different image file types and applying SEO best practices is essential for a professional, high-performing website. With the right format, smart naming, and properly optimised file sizes, your images will look great, load quickly, and support your SEO goals.