---
title: "Image Optimisation Checks — Lemwatch Help"
description: "Identify oversized, unoptimised, and poorly formatted images on your site."
canonical: "https://lemwatch.com/help/image-optimization"
source: "https://lemwatch.com"
---

# Image Optimisation Checks

> Identify oversized, unoptimised, and poorly formatted images on your site.

## Image Optimisation Checks

 Images are typically the largest assets on a web page. LemWatch scans your pages and identifies optimisation opportunities.

### What Gets Checked

 Check — Description —

 **Oversized images** — Images served at dimensions much larger than displayed —

 **Unoptimised formats** — Images using PNG/JPEG when WebP or AVIF would be smaller —

 **Missing dimensions** — Images without width/height attributes (causes layout shift) —

 **Total page weight** — Combined size of all images on the page —

 **Lazy loading** — Whether off-screen images use loading="lazy" —

### Results

 For each page checked, you'll see:

- Total images found on the page

- Oversized count — Images that could be resized

- Unoptimised format count — Images not using modern formats

- Total size in KB and potential savings in KB

- Per-image details — URL, current format, dimensions, and recommended changes

### How to Fix

 LemWatch provides actionable recommendations:

- Convert to WebP/AVIF — Modern formats are 30–50% smaller

- Resize to display dimensions — Don't serve 4000px images in 400px containers

- Add width and height — Prevents Cumulative Layout Shift (CLS)

- Enable lazy loading — Defer off-screen images

- Use a CDN with auto-optimisation — Cloudflare, Imgix, or Cloudinary

### Impact on Core Web Vitals

- LCP — Large unoptimised hero images directly increase Largest Contentful Paint

- CLS — Missing dimensions cause layout shifts as images load

- INP — Heavy images can block the main thread during decode


## Related

- [Help centre](https://lemwatch.com/help)
- [Core Web Vitals Explained](https://lemwatch.com/help/core-web-vitals)
- [Setting Performance Budgets](https://lemwatch.com/help/performance-budgets)
- [Lighthouse Reports](https://lemwatch.com/help/lighthouse-reports)
- [Font Loading Analysis](https://lemwatch.com/help/font-loading)
- [Cookie Compliance Checks](https://lemwatch.com/help/cookie-compliance)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [Incident Handoffs](https://lemwatch.com/help/incident-handoffs)