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How to calculate carbon footprint: carbon footprint calculator

People talk about carbon a lot. But what is a carbon footprint, and how can we use it to make positive change?

Essentially, your carbon footprint is the net carbon released as a result of everything that we consume, usually within a 12-month period. In a time of climate crisis such as this, the first step to making a positive change is to get the numbers on what our carbon footprint is, and what we can do to change it; by knowing your yearly footprint, you’ll see how you compare to the average, and start to find ways to reduce it.

Knowing this, the team at clever carbon wanted to create a calculator that makes it easy to find an estimate of your footprint. In this article, technical project manager Ben explains how the team built their own calculator so that you can make your own - and give ours a try!

Finding the Data

A good calculator starts with good data. There are a number of calculators on the market already, but we noticed a serious issue with them all. As clever carbon’s founder, Michelle Li, points out:

“The average US citizen has a footprint of around 17.5 tonnes of CO2 per year. The average footprint in Vietnam, however, is closer to 2 tonnes per year. You can’t apply the same calculations to everyone, because where we live makes such a huge difference to our footprint!”

That’s why we started by looking for data that would allow us to weight our results by country. Fortunately, this work had already been done for us: Global Carbon Atlas is a tool that surveys most of the world’s countries and produces various calculations - including the average person’s carbon footprint, by country! Awesome.

Now we had to figure out how much of this average footprint came from each consumption source. using various sources, we roughly narrowed them down to the following categories:

  • Home energy (19%)
  • Shopping (7%)
  • Diet (20%)
  • Commute (19%)
  • Flights (non-weighted)

You may have noticed that these don’t add up to 100%. There are several other minor sources of carbon in the average person’s lifestyle. The categories we’ve chosen add up to around two-thirds of the average person’s carbon footprint, so if someone were to give the “average” response to each question in our calculator, and we add a third for “miscellaneous consumption”, they’ll be given an average score for their country.

Note: we didn’t create questions in our calculator for every consumption source, because our quiz focuses on data that you’ll actually have control over. The amount of concrete used on your behalf per year, for example, is another part of your carbon footprint, but it’s not something you’ll be able to action, so we adde that to our generic “consumption” category.

How we did the calculations

I don’t want to get too far into the mathematics here, but it’s fairly straightforward. For each consumption category, I used a very simple formula:

X (CP)

This is where X is the score generated by the question you answered (varying between 0 and 2, with 1 being “average” for your country), C is the average footprint of your country, and P is the weighting percentage (in decimal form) that the particular category is of the whole figure.

The only exception to this is flights, which of course, are roughly the same in footprint no matter where you’re flying from. Here, we calculate based on the average footprint for an hour of flying, rather than using a country weighting.

That’s it for the math now, promise!

How to make your own quiz

Ok, so using the same data as us, you could make your own quiz! You could make additional calculations based specifically on your own country, or go into even more detail about different consumption sources.

However, there is a big advantage to doing an online quiz like ours. Being online and having a large audience all over the world means that finding out our carbon footprint is more social and engaging than going it alone. We encourage all readers to take our quiz and share the results online - after all, if we’re going to make a positive impact on climate change, it’s going to be a group effort, and we need to share our experiences along the way.

What’s more, using our quiz means that you’re helping to generate data that will help drive policy change in future. Already, the results of our quiz is helping us pick new campaigns to show people ways of reducing the most commonly high-consumption categories across the board.

Our findings

Since our quiz was launched, we’ve effectively surveyed over 1,500 individuals on their carbon footprint, from all around the world - and counting! The location of participants in our quiz depends on where our marketing and social media efforts go - but overall, our calculated average carbon footprint among all participants is now at 11.3.

Additionally, the average for a UK citizen, for instance, is also floating around the 8.5-tonne point - pretty much exactly as Global Carbon Footprint calculates. That’s great news for the accuracy of our quiz!

At just around 3 months in, we’re already using the info from the quiz to generate several new carbon footprint campaigns. Right now, we’re running a campaign on emails - yep, that’s right: your inbox has a footprint of its own! (Note: see our Instagram to take a look at our current content and campaigns for ways to reduce your footprint!)

What next?

If you haven’t already, take a look at our carbon quiz. It takes around 2 minutes, and at the end, you’ll get a nice badge that you can share around. Feel free to tag us @clever.carbon on Instagram - we love to engage with and talk to people that are using our quiz to do great things!

You could also take a look at our Carbon Footprint of Common Items, where we provide a run-down on the footprint of a variety of products and modes of travel, head to our Downloads for some cool stuff, or check out our Coffee Menu (share it with your favourite cafe - it looks neat and helps shoppers make better, more informed choices!)