Image optimisation best practices

Images are a common cause of slow websites and one of the easiest to fix. A few simple changes can improve performance.

Why it matters

Images affect:

• Page speed
• Core Web Vitals (especially LCP)
• SEO
• Accessibility
• Consistency of layout (CLS)

Unoptimised images slow everything down.

Best practices

1. Use WebP where possible

WebP typically offers smaller file sizes than JPEG or PNG with similar quality. Most modern platforms and plugins support it.

2. Compress before upload

Aim for roughly 150-250 KB for typical images. Large hero images can be slightly larger, but avoid multi‑MB uploads.

3. Size images correctly

Don’t upload 4000px images if the display size is 1200px or less. Match dimensions to how they’ll appear.

4. Descriptive filenames

Good: kitchen-fitting-example.jpg
Avoid: IMG_0319.JPG

Descriptive filenames help search engines and your own organisation.

5. Alt text

Describe the image for screen readers and when the image fails to load. Helps accessibility and SEO.

Tools

• TinyPNG – Web-based compression
• Squoosh – Browser-based compression and format conversion
• ShortPixel – WordPress plugin for automatic optimisation
• Shopify – Built-in optimisation; add optimised uploads on top

Next steps

Well-optimised images support speed, Core Web Vitals, and overall performance. See Website speed and Core Web Vitals.