Images can make a website feel polished, trustworthy and alive. They can also make it painfully slow.
The aim of image optimisation is simple: keep images looking good while reducing the amount of data a visitor has to download. For small business websites, blogs and online stores, this can improve user experience, search visibility and conversion rates.
Start before you upload
The biggest mistake is uploading a huge original image and expecting the website to fix it.
If your design displays an image at 900 pixels wide, there is usually no benefit in uploading a 5,000 pixel version. Resize images to sensible dimensions before they go into WordPress or your site builder.
This keeps your media library cleaner and helps avoid serving oversized files to visitors.
Choose the right format
Different image formats have different strengths.
JPEG is still useful for photographs where small file sizes matter. PNG is better for images that need transparency or crisp flat graphics, although it can become heavy if used for large photographs. SVG can work well for simple logos and icons. WebP is a strong modern option for many websites because it can offer good quality at smaller file sizes.
There is no single perfect format. The right choice depends on the image and how it is used.
Compress carefully
Compression reduces file size by removing unnecessary data.
Most websites do not need ultra-high-resolution, print-quality images. A carefully compressed image will often look almost identical to the original on screen while loading much faster.
For WordPress, image optimisation plugins can help automate this process, but it is still worth checking the results. Over-compression can create blurry edges, colour banding and other artefacts that make a site feel cheap.
Use responsive images
A visitor on a phone should not have to download the same large image as someone using a big desktop monitor.
Modern WordPress themes usually support responsive images, which means the browser can choose a more suitable image size for the visitor’s device. Make sure your theme handles this properly and avoid custom layouts that force unnecessarily large background images on every screen size.
Add meaningful alt text
Image optimisation is not only about speed.
Alt text helps screen readers describe images to visually impaired users. It can also help search engines understand the page. Keep it useful and descriptive rather than stuffed with keywords.
If an image is purely decorative, it may not need descriptive alt text. If it explains, sells or clarifies something, write alt text that reflects its purpose.
Be careful with sliders and galleries
Image-heavy sections can look impressive, but they often add weight.
Large hero sliders, auto-playing galleries and image-heavy product pages should be tested carefully. Ask whether every image is helping the visitor or simply slowing the page down.
For ecommerce sites, use clear product images, but keep thumbnails, category images and gallery files optimised.
Test the result
After optimising images, test important pages with tools such as PageSpeed Insights or GTmetrix. Look for warnings about oversized images, modern formats, lazy loading and layout shifts.
Good imagery should support the website, not get in the way of it.