---
title: CarbonGrader
url: 'https://byintention.co/resources/carbongrader'
markdown: 'https://byintention.co/resources/carbongrader.md'
date: '2026-11-05'
description: 'Use our free CarbonGrader tool to test your site, get an easy to understand score and a list of the most important fixes to make. Click to learn more!'
---

# CarbonGrader

![](https://byintention.co/user/media/headers/sustainable-web-design2-m.webp) # CarbonGrader

**Test your site for estimated carbon output, performance and check if it's running on green web hosting**

## How sustainable is your website?

Use our free tool to test your site, get an easy to understand score and a list of the most important fixes to make.

- Estimate the carbon output of a page
- Test performance - load time, page size etc
- Check if your hosting provider uses green energy

[Open CarbonGrader](https://grader.byintention.co/)

[![carbongrader tool screenshot](https://byintention.co/user/media/pages/carbongrader-screenshot-c.png)](https://grader.byintention.co/)

## Why does this matter?

Two main reasons - speed is good for users and SEO, and high traffic websites can use more energy than they need to.

### Speed

If a site takes too long to load your visitors might give up and go elsewhere - losing you that sale or enquiry. Search engines also love fast sites, and good page load times can contribute to better rankings.

### Energy Usage

Web pages have got bigger over time, taking longer to load and using more energy than they could do. Clean code, optimised images and techniques like 'lazy loading' can slash your website energy usage.

## How does CarbonGrader work?

We built a lightweight web app using open source and free tools, inspired by [EcoGrader](https://ecograder.com/).

The carbon output of a page is estimated by [CO2.js](https://www.thegreenwebfoundation.org/co2js/) (Apache-2.0) and Greencheck to see if the hosting provider uses sustainable energy or not. Both these are from the [Green Web Foundation.](https://www.thegreenwebfoundation.org/green-web-datasets/)

Performance is tested using the [Google PageSpeed Insights](https://developers.google.com/speed/docs/insights/v5/about) API and simplified - full results for a page can be seen from [Pagespeed Insights](https://pagespeed.web.dev/)

The app is coded in Javascript with the interface built using the [UIKit](https://getuikit.com/) framework (MIT) plus a sprinkling of custom CSS.

---

## Navigation

- Parent: [Resources](https://byintention.co/resources.md)
- Next: [Sustainable Design Resources](https://byintention.co/resources/sustainable-design-resources.md)