We calculate your carbon footprint by analysing your monthly transactions and matching them to their industry category (e.g. grocery, energy, transport).  

Each transaction amount is multiplied by an emissions factor per industry category to calculate the carbon footprint of that purchase. 

For example, if you spend £15 on a dress at an average high-street retailer, that could equate to a footprint of 16kg CO2. The same £15 spent on a dress from a charity shop could have a lower footprint of around 4kg CO2.  

The carbon footprint you see is a best estimate as we can only see your whole transaction amount, and not your basket level data. 

For example, if you spend £50 on grocery shopping, we will not know the individual items you have purchased. 

Your carbon footprint is calculated for the last rolling month based on the date you’ve chosen in your Spending settings. If you want to change your start date, go to Settings in the Spending tab, choose Set a date, and change the day.

We need three bits of data to calculate your carbon footprint: transactions, business names and emissions factors (EFs).

Once we have sorted your spend into categories based on business names, the Carbon Tracker compares those categories against a comprehensive list of business types and their EFs.

An EF is the amount of CO2 produced by £1 of spend, for a particular type of business. For example, a trip to a supermarket will on average produce 1.01 KG of CO2e per £ spent (less if you're a vegetarian). Extensive research has been conducted to calculate EFs that are as accurate as possible.

Despite considerable effort, the EFs still only represent the average emissions per transaction. We constantly work to improve their accuracy, for example by allowing companies to provide their own verified data.

You can view your monthly, calculated carbon footprint and your footprint's breakdown by categories so you can understand your environmental impact of every purchase you make. You can also see suggested changes you could make to reduce your footprint.

Your data is used to generate your carbon footprint; these results, are strictly used for the tracker only.