How to Optimise Images for Web Design and Search Engines

Ever clicked on a website that loads slower than your mum typing with one finger? Same. You pop the kettle on, feed the dog, rewatch a couple TikToks… and the page is still buffering like it’s 2003.

That, my friend, is an image optimisation fail.

And before you start blaming your theme or your hosting or Mercury being in Gatorade (whatever that means lol), I’m here to tell you, it’s probably your mahoosive images.

Because yes, beaut visuals matter. If you’re a creative biz owner or personal brand, your site needs to look like the moment. But if your images are massive, misnamed, or in the wrong format?

You’re basically rolling out the red carpet for high bounce rates, poor SEO rankings, and frustrated users smashing that ‘back’ button.

In this guide, I’m walking you through exactly how to optimise your images for web design AND search engines.

1. Resizing & Formatting Images the Right Way

Look, I love a big dramatic image as much as the next gal. But if your homepage banner is wider than the average 4K telly, we have a problem.

Resizing & Optimise Images for Better Performance

Big images = big problems.

They take forever to load — especially on mobile, where most of your audience is scrolling. They chew through bandwidth (which can literally cost you more if your hosting plan has limits), drag down your SEO because Google hates slow-loading pages, and create a frustrating user experience. And let’s be real… no one’s sticking around to watch a spinning loader wheel in 2025.

Here’s how to fix it:

• Your site builder or theme probably has image size guidelines — use them! Match the upload size to the display size. Don’t upload a 3000px-wide image if it’s only showing at 800px.

• Keep file sizes tight. Under 500KB for banners, under 100KB for smaller graphics.

• Use these free tools: Image Resizer or Compress JPEG.

Choosing the Best Image Format for Web & SEO

Your image format matters. It affects how fast your site loads, how crispy your visuals look, and whether Google gives you a lil SEO pat on the back or yeets you into digital oblivion.

The image format smackdown:

So… why is WebP the golden child right now?

It’s like the love child of JPEG and PNG. WebP gives you high-quality visuals and smaller file sizes, which means faster sites and happier Googlebots. Plus, it’s backed by Google, and you better believe that earns it brownie points in the SEO world. 

If you’re using WordPress, plugins like WebP Converter for Media make switching super simple.

2. Boosting SEO with Smart Image Optimisation

Because your image isn’t helping anyone if it’s named IMG_03829.

Optimising Image File Names & Alt Text

Uploading raw camera files straight to your site? STOP!

Google’s not going to magically know what IMG_4929.jpg is about. But it will take notice of a file called wedding-photographer-london.jpg.

Do this instead:

• Keep it short, specific, and keyword-friendly
• Use hyphens to separate words (like-this-not_this)
• Think: what would someone Google to find this image?

It’s a teeny-tiny change that gives your SEO a solid boost.

Alt text = the behind-the-scenes description of your image. It’s there for screen readers, but it also helps Google understand what the image is about.

Good alt text should:

• Actually describe what’s in the image (crazy concept, I know)
• Include your target keyword if it makes sense
• Sound like a human, not a keyword robot

Here’s an example…

Let’s say I want to add the above image to my portfolio page. 

❌ Bad Alt Text: performance report

It’s vague, too short, and doesn’t explain what kind of report or what’s shown on screen.

✅ Good Alt Text: Laptop displaying a GTmetrix website speed report with performance and structure scores of 98% for alpinefitpt.com

• Describes the scene and what’s on screen
• Includes relevant keywords like “website speed report” and the name of the site being analysed
• Useful for screen readers and SEO alike

If your alt text feels like you’re begging for SEO points, delete it and try again.

💡 Want to find the exact questions your dream clients are Googling?
I break down how to mine the People Also Ask section for killer content ideas (and SEO gold).

Using Unique Images to Stand Out

I look at multiple websites a day (it’s kinda my job), and I see the same stock images, day in and day out. There’s nothing wrong with them, but they certainly don’t do anything to help you stand out. 

Here’s why original images are:

• Google prefers unique content (including visuals)
• They’re more likely to show up in image search
• They actually reflect your brand — not some generic Pinterest aesthetic

Now, I’m not suggesting you go and pay a couple of grand for a professional shoot (unless you want to). Start with what you’ve got. 

Snap a few selfies. Screenshot your processes, results, client messages, anything. Create some infographics or product mockups. If you click around on my site, you’ll see lots of these, and it makes them waaaay more on brand!

Adding Structured Data for Image Search Visibility

Okay, now we’re entering nerd territory, but it’s worth it.

Structured data (aka schema markup) = a little bit of code that helps Google understand your images better. Think of it as giving your visuals their own elevator pitch.

I like to use it for:

• Portfolio pieces
• Product images
• Tutorials or anything step-by-step-y

How to do it:

→ If you’re using WordPress, plugins like Yoast or Rank Math can help

→ Feeling techy? Google’s guide walks you through it

Not essential, but a lovely cherry on your SEO cake. (And I bet your competitors aren’t doing it.)

3. Enhancing Site Speed with Compression & Delivery

Compressing Images for Faster Loading Times

Compression = making your images smaller without turning them into a blurry mess.

There are two types:

• Lossy: smaller files, slightly lower quality (still totally fine for most websites)
• Lossless: better quality, bigger files

If you’re not a photographer or running an art gallery, lossy is usually all you need.

A few tools to try:

• Smush – free WordPress plugin that does the job
• WebP Converter for Media – great if you want to serve images in WebP format
• Or check your hosting — platforms like SiteGround often handle this for you

Don’t overthink it. If your image still looks good and your site loads faster, you’re winning.

Serving Images via a CDN (Content Delivery Network)

In plain English? It stores your images on a bunch of servers around the world, so wherever your visitor is, they get the file from the nearest one — not from your one sad little server in London trying to do all the heavy lifting.

Benefits:

• Faster load times
• Less strain on your hosting
• Better performance if you’ve got a global audience (or one big launch coming up)

Try these:

• Cloudflare (good all-rounder)
• BunnyCDN (great for image-heavy sites)
• SiteGround CDN if you’re already hosting with them — no extra setup needed

Enabling Lazy Loading for Faster Page Loads

Lazy loading = only loading images when they’re actually needed. So if someone doesn’t scroll all the way down your page, those images don’t load at all.

It’s an easy win for speed — and honestly, most websites should be doing it by default.

Most caching plugins support lazy loading… here’s a quick breakdown of some that do:   

I recommend and use Siteground for my website host and for my clients. 

4. Testing & Refining Your Image Optimisation Strategy

Testing Image Performance & Fixing Issues

Before you start blaming your hosting or theme, check your images. They’re usually the main culprit when your site speed goes off a cliff.

Here’s how to find out what’s dragging things down:

Run your site through:

• Google PageSpeed Insights — tells you exactly which images are causing problems
• GTmetrix — shows your site’s loading breakdown (plus nice little speed grades that feel like a school report, but for your website)

What those PageSpeed Insights diagnostics actually mean (in human-speak):

When you run your site through PageSpeed Insights, you’ll probably get hit with a few red flags in the “Diagnostics” section. 

Here’s what the most common ones actually mean and what you can do about them:

Largest Contentful Paint element

This refers to the biggest visible thing on your page (usually a big image, banner or video) and how long it takes to load. If it’s slow, your entire site feels slow.

FIX: Optimise your hero images and make sure they load fast.

Minimise main-thread work

Your browser’s trying to juggle all the scripts, animations, and functions on your site — and it’s overwhelmed.

FIX: Reduce or defer JavaScript, ditch unnecessary animations, and avoid too many third-party tools.

Avoid an excessive DOM size

The DOM is basically your page’s blueprint. If it’s got thousands of nested elements, the browser needs more time to sort it all out.

FIX: Clean up your page structure and avoid bloated page builders or endless stacked sections.

Eliminate render-blocking resources

These are files (like CSS or JavaScript) that have to load before anything else can appear. They block the rendering of the page.

FIX: Use async/defer, inline critical CSS, or let your speed plugin handle the heavy lifting.

Serve images in next-gen formats

Google wants you to use WebP instead of JPEG/PNG — they’re faster to load without losing quality.

FIX: Convert your images to WebP and re-upload.

Efficiently encode images

That’s Google-speak for “your images are way too big.”

FIX: Compress images before uploading with TinyPNG, ImageOptim, or Squoosh.

Defer offscreen images

If images below the fold are loading before anyone scrolls to them, it slows things down.

FIX: Turn on lazy loading so they load only when needed.

Image Optimisation Tools to Use

Here’s a quick rundown of the best tools to help you keep things optimised moving forward — whether you’re DIY-ing or semi-ignoring your tech stack (no judgement).

Final Thoughts

Look, image optimisation might not be the sexiest part of web design, but it’s hands down one of the most underrated ways to boost your site’s speed, rankings, and overall user experience.

And if you want to keep that SEO momentum going? Image optimisation is just one piece of the puzzle. So if you’re ready to level up the rest of your website’s SEO without falling down a 37-tab rabbit hole…

Grab my FREE SEO Checklist  — packed with quick, practical tips to help you get found on Google, boost your visibility, and finally feel like your website’s doing some of the heavy lifting for your business.

You don’t need to become an SEO expert. You just need a plan. And this checklist is a damn good place to start.

FAQs About Image Optimisation

How do you optimise an image for web use?

Start by resizing it to the actual dimensions it’ll be displayed at — no oversized uploads for tiny spots. 

Then compress it (lossy or lossless depending on your needs), choose the right format (WebP if possible), and give it a clear, descriptive file name. Bonus points for adding alt text and enabling lazy loading.

How do I optimise my image for SEO?

Use a keyword-rich file name (no more IMG_3829.jpg), write proper alt text that describes the image naturally, and serve your images in next-gen formats like WebP. Make sure your file size is as small as possible without compromising quality — because Google cares about both speed and accessibility.

Where do web designers get their images?

Some use custom brand photography (which is always ideal), others lean on high-quality stock image sites (I personally really like https://kaboompics.com/  Styled Stock Society, https://www.pexels.com/  and Death to Stock). If you’re using stock, always crop or customise it to fit your brand — and avoid the ones you’ve seen 4 million times before.

What image format is best for SEO?

WebP is currently the best choice for SEO. It keeps file sizes small while maintaining quality — which means faster load times, better user experience, and a little SEO love from Google.

Is PNG or JPEG better for SEO?

It depends on the image. JPEGs are best for photos because they’re smaller in size. PNGs are great for graphics with transparency or fine detail but tend to be heavier. If you’re choosing between the two for speed? JPEG wins. But really… just use WebP where you can.

Should all website images be WebP?

Ideally, yes. WebP offers better compression than JPEG or PNG, which helps your site load faster — and that means better SEO. 

Most modern browsers support it now, and you can convert your images easily using WordPress plugins like WebP Converter for Media.