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Your PageSpeed Insights Score Is Low Because of Your Images (Here's How to Fix It)

PageSpeedWeb VitalsSEOBeginners

Your PageSpeed Insights Score Is Low Because of Your Images (Here's How to Fix It)

You just ran a PageSpeed Insights report on your website, and the score came back in the yellow or red zone. Your boss is asking questions. Your SEO team is concerned. And you're wondering what you're supposed to do about it.

Here's the good news: there's a very good chance your images are the main problem. And unlike fixing code or server issues, optimizing images is something you can actually do yourself - no developer required.

What Is PageSpeed Insights?

If you're not familiar with it, PageSpeed Insights is Google's free tool that measures how fast your website loads. It gives you a score from 0-100 and tells you what's slowing your site down.

Why does this matter?

  • Google uses it for rankings - Faster sites rank higher in search results
  • It affects conversions - Slow sites lose customers
  • It impacts user experience - Nobody likes waiting for pages to load

When you run a report, you'll typically see scores for different metrics called "Core Web Vitals." These are Google's way of measuring real user experience.

The Three Web Vitals That Matter

Google focuses on three main metrics:

1. Largest Contentful Paint (LCP)

This measures how long it takes for the biggest element on your page to load - and that's usually an image. A hero image, product photo, or banner.

What Google wants: Under 2.5 seconds What most sites have: 3-5 seconds Why: Images are too big

2. First Input Delay (FID) / Interaction to Next Paint (INP)

This measures how quickly someone can interact with your page. Heavy images can slow this down because the browser is busy loading them.

What Google wants: Under 100ms for FID, under 200ms for INP What most sites have: 200-500ms Why: Browser is overwhelmed processing large files

3. Cumulative Layout Shift (CLS)

This measures how much your page jumps around while loading. Images without proper dimensions cause this.

What Google wants: Under 0.1 What most sites have: 0.2-0.4 Why: Images load slowly and shift content

How Images Tank Your Score

When you run PageSpeed Insights, you'll often see warnings like:

  • "Properly size images"
  • "Serve images in next-gen formats"
  • "Defer offscreen images"
  • "Reduce render-blocking resources"

Most of these come down to one thing: your images are too large.

Real Example

Let's say you're a content editor for an e-commerce site. You uploaded a new product page with 8 photos:

What you uploaded:

  • 8 product photos straight from the photographer
  • Each image: 2-3MB
  • Total: 20MB of images

What happens:

  • PageSpeed Insights score: 35 (red)
  • LCP: 6.2 seconds
  • Warning: "Serve images in next-gen formats"
  • Warning: "Properly size images"

What Google (and your visitors) experience:

  • Slow load time
  • Poor mobile experience
  • High bounce rate
  • Lower search rankings

The Simple Fix: Convert to WebP

PageSpeed Insights specifically recommends "serving images in next-gen formats." What does that mean? It means WebP.

WebP is a modern image format that makes your files 25-50% smaller with no loss in quality. This directly improves your PageSpeed Insights score.

The Impact on Your Metrics

When you convert your images to WebP:

Largest Contentful Paint (LCP)

  • Before: 5.2 seconds
  • After: 2.1 seconds
  • Improvement: 60% faster

Overall PageSpeed Score

  • Before: 35 (red)
  • After: 89 (green)
  • Improvement: From failing to passing

Page Weight

  • Before: 8MB
  • After: 2.8MB
  • Improvement: 65% reduction

Step-by-Step: How to Improve Your Score

You don't need to know how to code. Here's exactly what to do:

Step 1: Run Your Current Report

  1. Go to PageSpeed Insights
  2. Enter your website URL
  3. Click "Analyze"
  4. Take a screenshot of your current score (you'll want to compare later)

Step 2: Identify Your Image Problems

Look for these warnings in the report:

  • "Serve images in next-gen formats" - This is telling you to use WebP
  • "Properly size images" - Your images are too large
  • "Eliminate render-blocking resources" - Images are slowing down the initial load

Click on each warning to see which specific images are causing problems.

Step 3: Download Your Images

Go to your website and download the images that PageSpeed Insights flagged. Usually these are:

  • Hero/banner images
  • Product photos
  • Blog featured images
  • Large background images

Step 4: Convert to WebP

  1. Go to your WebP converter tool
  2. Upload each image
  3. Convert to WebP format
  4. Download the converted files

Convert your images now → It takes about 30 seconds per image.

Step 5: Replace Your Images

Upload the new WebP versions to your CMS (WordPress, Shopify, etc.) and replace the old images.

Important: Keep the same filenames or update the references in your pages. Most modern CMS platforms handle WebP automatically.

Step 6: Run PageSpeed Insights Again

  1. Go back to PageSpeed Insights
  2. Enter your URL again
  3. Click "Analyze"
  4. Compare your new score to your screenshot from Step 1

You should see a significant improvement, especially in LCP.

Real Results from Real Sites

E-commerce Product Page

Before WebP:

  • PageSpeed Score: 42
  • LCP: 4.8 seconds
  • 12 warnings about images

After WebP:

  • PageSpeed Score: 91
  • LCP: 1.9 seconds
  • 2 minor warnings

Business impact: 23% increase in mobile conversions

Company Blog

Before WebP:

  • PageSpeed Score: 38
  • LCP: 5.2 seconds
  • High bounce rate on mobile

After WebP:

  • PageSpeed Score: 87
  • LCP: 2.3 seconds
  • 15% decrease in bounce rate

Business impact: Better Google rankings, more organic traffic

Marketing Landing Page

Before WebP:

  • PageSpeed Score: 51
  • LCP: 3.9 seconds
  • Slow mobile experience

After WebP:

  • PageSpeed Score: 94
  • LCP: 1.8 seconds
  • Fast on all devices

Business impact: 31% improvement in ad campaign conversion rate

What Your Boss/Team Will Notice

When you improve your PageSpeed Insights score by optimizing images:

Immediate Benefits:

  • Green score instead of red/yellow
  • Faster page load times
  • Better mobile experience
  • Fewer bounce-backs

Business Benefits:

  • Higher search rankings (Google rewards fast sites)
  • More conversions (fast sites sell more)
  • Lower bounce rates (people stick around)
  • Better ROI on ad spend (fast landing pages convert better)

SEO Benefits:

  • Improved Core Web Vitals
  • Better mobile-first indexing
  • Higher quality score for ads
  • Competitive advantage in search

Common Questions

"Will this actually improve my PageSpeed score?"

Yes! Images are typically responsible for 60-80% of page weight. Converting to WebP directly addresses the "serve images in next-gen formats" warning, which is one of the biggest score killers.

"How long does this take?"

For a typical page with 5-10 images, about 30-45 minutes total. The conversion itself takes seconds per image.

"Do I need to convert every image on my site?"

Start with the most important pages - homepage, product pages, top blog posts. Focus on the images that PageSpeed Insights specifically flags.

"Will my images look different?"

No! WebP maintains the same visual quality. Your images will look identical to visitors, just load much faster.

"What if I'm using WordPress/Shopify/Wix?"

Most platforms support WebP. You can usually just upload the WebP files like any other image. Some platforms even convert automatically.

"Can I automate this?"

Yes! Once you see the results, you can set up processes to convert all new images to WebP before uploading them. But start manually to see the impact.

The Mobile Factor

Here's something important: PageSpeed Insights shows you both desktop and mobile scores. Mobile is more important because:

  • 60%+ of traffic comes from phones
  • Google uses mobile-first indexing
  • Mobile connections are slower

Heavy images hurt mobile scores more than desktop. WebP fixes this because smaller files load faster on mobile connections.

Mobile score improvement:

  • Before: 28 (red)
  • After: 85 (green)

This is where you'll see the most dramatic change.

Beyond the Score

While PageSpeed Insights scores are important, remember what they represent: real user experience.

When someone visits your site on their phone:

  • They're probably on mobile data
  • They might have a slow connection
  • They'll leave if it takes more than 3 seconds

Converting to WebP means:

  • Faster load times for real users
  • Better experience for mobile customers
  • More people actually seeing your content
  • Higher chances of conversions

The score is just Google's way of measuring that.

Action Plan for Project Managers

If you're managing a website project, here's how to approach this:

Immediate (This Week)

  1. Run PageSpeed Insights on your key pages
  2. Identify the worst-performing pages
  3. Convert the flagged images to WebP
  4. Re-run the reports and document improvements

Short-term (This Month)

  1. Convert all images on high-traffic pages
  2. Update your content guidelines to include WebP
  3. Train content editors on conversion process
  4. Monitor PageSpeed scores weekly

Long-term (Ongoing)

  1. Make WebP conversion part of your publishing workflow
  2. Set up monitoring for Core Web Vitals
  3. Review and optimize new pages regularly
  4. Track the correlation between scores and business metrics

Start With One Page

Don't try to fix your entire site at once. Start with one important page:

  • Your homepage
  • Your best-selling product
  • Your most-visited blog post
  • Your main landing page

Convert those images, run PageSpeed Insights again, and see the difference. Once you see the results, you'll be motivated to do more.

Convert your first image now → Pick your most important page and start there. It takes less than 5 minutes to see real improvement.

The Bottom Line

You don't need to be a developer to improve your PageSpeed Insights score. You don't need to mess with code or configure servers. Most of the time, you just need to convert your images to a better format.

WebP is that format. It's what Google recommends when it warns about "next-gen formats." It's what makes your LCP score go from red to green. And it's what will improve your user experience, search rankings, and conversion rates.

The best part? It's something you can do yourself, right now, and see results immediately.

Start improving your PageSpeed score → Convert your images to WebP and watch your scores climb into the green zone.

Your SEO team, your users, and your bottom line will thank you.