What Image Files Are Best For SEO?

But when it comes to SEO, image files are more than just pretty pictures – they’re a key component in ensuring your page loads quickly, ranks well, and enhances conversion rates and user experience. 

In this article, we’re going to explore which image formats are best for SEO, why they matter, and how you can leverage them to improve your rankings.

Why Image Optimisation is Crucial for SEO

Before we jump into the ‘which image file format’ debate, let’s remind ourselves why image optimisation matters in the first place. There are a few reasons SEO professionals should care:

Page Speed: Google has made it clear that site speed is a ranking factor. The slower your site loads, the more likely you are to lose visitors, leading to higher bounce rates. 

Large, unoptimised image files can slow down your page, and this is especially problematic for mobile users, where speed is even more critical.

User Experience: Proper image optimisation leads to better user experience. Images that load quickly contribute to a seamless browsing experience, which directly impacts engagement metrics. 

We know that when users are happy, Google’s algorithms tend to be happy too.

Search Engine Crawling & Indexing: Search engines can’t ‘see’ images in the same way humans do. They rely on metadata (alt text, file names, etc.) to understand the content of an image. 

The better the optimisation, the easier it is for search engines to crawl, index, and rank the images on your website.

Mobile Optimisation: With the increasing number of mobile searches, responsive images are now more important than ever. 

Images that load quickly and display correctly on all devices are vital for SEO, especially since Google moved to mobile-first indexing.

Now that’s explained, let’s dig into the formats that will best serve your SEO needs.

So Which Image Formats Should You Use?

There are a wide range of image formats that are used throughout the world of SEO. Discover the best image formats for SEO that improve site speed, user experience, and search engine rankings:

WebP (Web Picture Format)

Best for: Image-heavy websites that need to optimise both quality and load speed.

WebP is the new kid on the block, developed by Google to reduce image file sizes while maintaining high quality. It’s rapidly gaining popularity as a superior alternative to JPEG and PNG, thanks to its impressive compression capabilities.

Why WebP is SEO-Friendly:

• Superior Compression: WebP uses both lossy and lossless compression, resulting in smaller file sizes compared to JPEG and PNG without sacrificing too much quality. This is crucial for improving load times, which is a major factor in SEO.
• Faster Load Times: With WebP’s smaller file sizes, your images will load faster – this contributes to improved user experience, lower bounce rates, and higher rankings.

Browser Support: While WebP is supported by most modern browsers (Chrome, Firefox, Edge, Opera), it still lacks full support in Safari. For now, you’ll need a fallback strategy for Safari users, but WebP is a great choice if your audience uses compatible browsers.

When to Use WebP:

• Image-heavy sites (eCommerce, media, portfolio websites)
• When both image quality and load speed are a priority
• Mobile-optimised sites, where speed is especially crucial

Our Pro Tip – Use WebP for images wherever possible, but be sure to implement fallback images in JPEG or PNG for Safari users.

JPEG (Joint Photographic Experts Group)

Best for: Photographs, detailed images, and content-heavy visuals.

As any seasoned SEO pro knows, JPEGs are the workhorses of image formats. With their ability to handle high-resolution images with minimal file sizes, JPEGs are the go-to format for photos and detailed visuals.

Why JPEG is SEO-Friendly:

• Compression Efficiency: JPEGs are highly compressed, which means you can keep file sizes small without sacrificing too much quality. Smaller file sizes lead to faster loading times – a key ranking factor for Google.
• Versatility for Photographs: When it comes to photographs, JPEG is your best option. It handles complex images with gradients, shadows, and lots of color variation without turning them into pixelated nightmares.
• Universal Support: You won’t find a device or browser that doesn’t support JPEG. No need to worry about compatibility issues, ensuring your images look great for all users.

When to Use JPEG:

• Photographs (product images, blog post photos, lifestyle images, etc.)
• Detailed images with lots of colors
• Large images or images with fine details that require efficient compression

Our Pro Tip – Be cautious about using high-resolution JPEGs for web use. Stick to optimised sizes – remember, larger images can drag your page speed down, and speed is a dealbreaker in SEO.

PNG (Portable Network Graphics)

Best for: Logos, graphics with transparency, and images with sharp lines.

If JPEG is the workhorse, PNG is the detail-oriented craftsman. PNG is perfect for images that need to retain transparency or need sharp lines and high-quality graphics, such as logos, icons, and UI elements.

Why PNG is SEO-Friendly:

• Lossless Compression: Unlike JPEGs, PNGs use lossless compression, meaning no image quality is sacrificed during compression. This makes PNGs ideal for images that require perfect clarity, like logos and icons.
• Transparency Support: PNGs are the only major image format that supports transparency, which is essential for layering images on various backgrounds (think logos, overlays, and icons).
• Sharper Image Quality: PNGs excel at displaying images with sharp lines and text without the fuzziness that can sometimes occur in JPEGs
  
  

When to Use PNG:

• Logos and icons
• Images with sharp lines, text, or small graphics
• Visual elements that require transparency

Our Pro Tip –  While PNGs are perfect for sharp, high-quality images, they tend to have larger file sizes. To balance quality and file size, make sure you’re not uploading overly large PNGs. Compress them to fit the web without losing integrity.

SVG (Scalable Vector Graphics)

Best for: Logos, icons, illustrations, and other vector-based images.

SVGs are a vector-based image format, meaning they’re not made up of pixels like JPEGs and PNGs. Instead, they’re created with XML code, allowing for infinite scalability without losing quality. When your design involves clean lines and flat colors, SVG is definitely your go-to.

Why SVG is SEO-Friendly:

• Scalable Quality: SVGs maintain perfect quality regardless of size, making them ideal for responsive web design and high-resolution displays (think Retina screens).
• SEO-Optimised: Since SVGs are XML-based, they can be crawled by search engines just like text. You can include metadata, alt text, and keywords directly within the SVG code, giving it an SEO edge.
• Lightweight for Simple Images: For simple graphics like logos or icons, SVGs tend to have smaller file sizes compared to other formats, making them a great choice for fast loading times.

When to Use SVG:

• Logos and icons
• Simple illustrations, diagrams, and vector graphics
• When you need resolution-independent images for responsive designs

Our Pro Tip – Avoid using SVGs for complex images or detailed photos, as they can become large and unwieldy. Stick with them for clean, scalable visuals.

GIF (Graphics Interchange Format)

Best for: Simple animations and small dynamic content.

Let’s be real: GIFs are here to stay. While they’re not typically the format of choice for high-quality images, they serve their purpose when it comes to simple animations and lightweight, dynamic content.

Why GIF is SEO-Friendly:

• Lightweight for Short Animations: For short animations or looping content, GIFs are a great option. They tend to have smaller file sizes compared to video formats, making them ideal for lightweight, fun elements on your website.
• Universal Support: GIFs are supported across all browsers and devices, ensuring your animations work everywhere. 

When to Use GIFs:

• Short, simple animations (like banner ads, product showcases)
• Dynamic visual content to engage users
• When you want to add a bit of fun or humor to your website

Our Pro Tip – Avoid using GIFs for complex or high-quality content, as they tend to result in larger file sizes and lower quality compared to other formats.

Final Thoughts – Choosing the Right Image Format for SEO

Ultimately, the bottom line is this: there’s no one-size-fits-all answer when it comes to image formats for SEO. The best image format for your website will depend on the type of content you’re working with, your priorities in terms of speed and quality, and your target audience’s browsing habits – all of which must be taken into consideration when selecting the right image format for you. Here’s a brief summary to help you make the right choice:

• WebP: Great for modern, image-heavy sites that prioritise speed.
• JPEG: Best for detailed photos and images with many colors.
• PNG: Ideal for logos, icons, and transparent images.
• SVG: Perfect for scalable logos, icons, and vector-based graphics.
• GIF: Best for lightweight animations and dynamic content. 

Optimising your images is not just about picking the right format – it’s about finding the balance between image quality, file size, and page load speed. So go ahead, make those image optimisations, and give your website the SEO boost it deserves.

And remember: in the ever-evolving world of Technical SEO, staying ahead of the curve with modern tools and strategies – like WebP – is one way to keep your brand the purple cow that stands out in a field of SEO agencies. Happy optimising, folks.

If you need help with image optimisation to improve your rankings and optimise your conversion rate, reach out to our SEO experts today!