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Image Optimisation Guide: How to Speed Up Your Website Without Losing Quality (2026)
Images make websites more engaging, help showcase products and services, and improve the overall user experience. However, large or unoptimised images are one of the most common reasons websites load slowly. Slow-loading pages can frustrate visitors, increase bounce rates, and negatively impact your SEO.
Image optimisation is the process of reducing image file sizes while maintaining good visual quality. Properly optimised images help your website load faster, improve Core Web Vitals, and provide a better experience for users across all devices.
In this guide, we’ll explain everything you need to know about image optimisation and how to improve your website’s performance.
Quick Summary: Image Optimisation Guide
- 1. Compress images before uploading
- 2. Choose the correct image format
- 3. Resize images to the required dimensions
- 4. Use modern formats like WebP or AVIF
- 5. Enable lazy loading
- 6. Add descriptive alt text
- 7. Use responsive images
- 8. Optimise image file names
- 9. Serve images through a CDN
- 10. Test image performance regularly
What Is Image Optimisation?
Our Image Optimisation Guide shows you how to reduce image file sizes, improve Core Web Vitals, and speed up your website without losing quality.
Optimisation involves:
- Compressing image files
- Resizing images
- Choosing the correct format
- Using responsive images
- Improving image delivery
The goal is to create fast-loading pages without noticeably reducing image quality.
Why Image Optimisation Matters
Optimised images provide several important benefits:
- Faster website loading
- Better user experience
- Improved Core Web Vitals
- Lower bandwidth usage
- Better mobile performance
- Reduced server load
- Improved SEO
- Higher conversion potential
For many websites, images account for the largest portion of page size, making optimisation one of the most effective ways to improve performance.
10 Ways to Optimise Website Images
1. Compress Images Before Uploading
Compression reduces file size while maintaining visual quality.
Benefits include:
- Faster loading pages
- Reduced storage usage
- Better website performance
- Improved mobile experience
Choose a compression level that balances quality and file size.
2. Resize Images Properly
Avoid uploading images much larger than the space where they’ll be displayed.
For example:
- If an image displays at 1200 × 800 pixels, uploading a 5000 × 3500 pixel image only increases file size unnecessarily.
Resizing images before uploading helps reduce page weight and improves loading times.
3. Choose the Right Image Format
Different image formats are suitable for different types of content.
JPEG
Best for:
- Photographs
- Product images
- Large banners
PNG
Best for:
- Logos
- Graphics
- Images requiring transparency
WebP
Best for:
- Most modern websites
- Smaller file sizes
- High-quality images
AVIF
Best for:
- Maximum compression
- Excellent image quality
- Modern browsers
Selecting the right format can significantly reduce file sizes.
4. Use WebP or AVIF Where Possible
Modern image formats such as WebP and AVIF provide better compression than traditional JPEG or PNG files.
Benefits include:
- Smaller file sizes
- Faster loading
- Improved Core Web Vitals
- Better mobile performance
Most modern browsers support these formats.
5. Enable Lazy Loading
Lazy loading delays the loading of images until they’re needed.
Instead of downloading every image immediately, images below the visible part of the page load only when visitors scroll down.
Benefits include:
- Faster initial page load
- Lower bandwidth usage
- Improved Largest Contentful Paint (LCP)
6. Use Responsive Images
Visitors access websites on many different screen sizes.
Responsive images ensure that:
- Mobile users receive smaller images
- Desktop users receive larger versions when needed
- Devices don't download unnecessarily large files
This improves performance across all devices.
7. Optimise Image File Names
Descriptive file names help search engines understand your images.
Instead of:
IMG12345.jpg
Use:
website-design-london.jpg
Good file names:
- Describe the image
- Include relevant keywords naturally
- Use hyphens between words
Avoid keyword stuffing.
8. Add Alt Text
Alternative (alt) text describes images for:
- Search engines
- Screen readers
- Accessibility
Example:
Good alt text:
“Website designer creating a responsive business website”
Avoid generic descriptions such as “image” or “photo”.
9. Deliver Images Through a CDN
A Content Delivery Network (CDN) serves images from servers closer to your visitors.
Benefits include:
- Faster image delivery
- Reduced server load
- Better global performance
- Improved user experience
This is especially useful for websites with international visitors.
10. Test Image Performance Regularly
Website performance changes over time.
Review:
- Large image files
- Broken images
- Compression quality
- Core Web Vitals
- Mobile performance
Regular testing helps identify opportunities for improvement.
Best Image Formats
| Format |
Best For |
Advantages |
|---|---|---|
|
JPEG |
Photos | Small file size and wide compatibility |
|
PNG |
Logos & graphics |
Supports transparency |
|
WebP |
Most websites | Better compression than JPEG and PNG |
|
AVIF |
Modern websites | Excellent compression and image quality |
|
SVG |
Icons & simple graphics | Scales without losing quality |
Image SEO Best Practices
Improve your image SEO by:
- Using descriptive file names
- Adding relevant alt text
- Compressing images
- Using modern formats
- Creating responsive images
- Including images that support your content
- Avoiding duplicate image files
Image optimisation helps both visitors and search engines understand your content.
Common Image Optimisation Mistakes
Avoid these common issues:
- Uploading oversized images
- Using the wrong file format
- Forgetting alt text
- Using generic file names
- Disabling lazy loading unnecessarily
- Compressing images too aggressively
- Ignoring mobile optimisation
- Not using responsive images
Small improvements across multiple images can significantly improve website performance.
Image Optimisation Checklist
- Images compressed
- Correct image format selected
- WebP or AVIF used where supported
- Images resized correctly
- Lazy loading enabled
- Responsive images configured
- Alt text added
- Descriptive file names used
- Images delivered through a CDN (if appropriate)
- Performance tested regularly
Recommended Image Optimisation Tools
Popular tools include:
- TinyPNG
- Squoosh
- ShortPixel
- Imagify
- EWWW Image Optimizer
- Smush
- Optimole
Many WordPress plugins can automatically compress and convert images as they’re uploaded.
Frequently Asked Questions
What is image optimisation?
Image optimisation is the process of reducing image file sizes while maintaining good visual quality, helping websites load faster and perform better.
Which image format is best for websites?
It depends on the image. JPEG works well for photographs, PNG is useful for graphics with transparency, WebP is an excellent all-round format for modern websites, and AVIF offers even better compression where supported.
Does image optimisation improve SEO?
Yes. Optimised images improve page speed, Core Web Vitals, and user experience. Descriptive file names and alt text also help search engines understand your content.
Should I resize images before uploading?
Yes. Upload images close to the size they’ll be displayed on your website. This reduces file size and improves loading speed.
What is lazy loading?
Lazy loading delays the loading of images until they’re about to appear on the visitor’s screen. This improves initial page load times and reduces unnecessary downloads.
Optimise Your Website Images with GetWebsite.io
Proper image optimisation is one of the simplest ways to improve website speed, user experience, and SEO. At GetWebsite.io, we provide professional Website Speed Optimisation Services for UK businesses, including image compression, WebP conversion, lazy loading configuration, Core Web Vitals improvements, CDN setup, and ongoing performance optimisation. Whether you run a business website or an eCommerce store, our team can help ensure your images load quickly while maintaining excellent visual quality.
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