Carbon Calculators – An Evaluation

Carbon calculators are one of the strategies that have popped up over the last few years to engage people in reducing their carbon emissions. The idea is that if you know how much you’re producing, and how, then that’s the first step to making changes. It’s a good idea but I’m doing a (very) quick evaluation on the most popular calculators to see how accurate and effective they are.

1. http://carboncalculator.direct.gov.uk/index.html

This is the first one I looked at. As it’s “.gov” I would presume it’s government endorsed. I’m straight away impressed by the swanky graphics, and it’s very user friendly. There’s handy “I don’t know” options for most questions which I made pretty good use of. I also guessed the age of my house. It includes heating and lighting your home, running appliances, and personal travel. It was all going so well until the last section… Travel really threw all notions of accuracy out the window.  You see, I said that I don’t own a car and don’t fly, both true enough, but then there was this section where you were meant to put in your frequent public transport journeys. I don’t have any regular journeys as such, so I didn’t fill it out. It reassured me that an estimation would be made for me based on national averages. Sadly I don’t think they did a very good job of this as my travel was then estimated at “0 tonnes per year”. I know this isn’t true because I do travel by bus and train on occasion and also get lifts in other people’s cars.

This error resulted in my allegedly getting 0.7 tonnes per year as my carbon footprint. I wish that were true… By the way it also tells me the national average for the UK is 4.46 tonnes.

After the result was shown there was a “next steps” section for reducing your footprint, which I think is a helpful addition.

So… Pretty, easy and eager to help, but completely inaccurate and therefore slightly useless…


2. http://www.carbontrust.co.uk/cut-carbon-reduce-costs/calculate/carbon-footprinting/Pages/carbon-footprinting.aspx

This was my second port of call. However, I didn’t get to calculate my footprint because it seemed to just be for organisations, not individuals.

I will also say that it was very awkward and not at all easy to use. You had to register before you could do anything, and the questions were difficult.


3. http://www.carbonfootprint.com/calculator.aspx

I liked this calculator because it was the only one that clearly told you it’s sources of estimation. On the front page there’s a little list of organisations  (e.g. DEFRA) that they’ve got data from. It also confessed that the Secondary Emissions section will be less accurate than the Primary. I appreciate this kind of transparency.

It seems fairly transport orientated, with sections for house, flights, car, motorbike, bus & rail and secondary emissions. I actually only filled out the Secondary part as the others were quite hard. I don’t think many people know how many kWh their fridge uses per year, or how many miles they travel by bus per year… If I wanted to use this calculator properly I would need to spend a lot longer gathering information. I guess that is fair enough and if I did actually take the trouble to find out all the data needed then perhaps I would be awarded with an estimation that has some bearing on my actual carbon usage.

Any way, my result for the Secondary Emissions section  was 1.68 tonnes per year. Note: this is more than the whole supposed figure from the first calculator.

I would say this is a good calculator to use if you’re happy to put in the work for a serious calculation exercise, but for the layman it is a bit unworkable.


4. http://footprint.wwf.org.uk/

This last calculator has very nice graphics and is very user friendly. It has sections for food, travel, home and stuff. This makes it more well-rounded than the others. My only real criticism is that in the stuff section the ranges are very wide. For example, the multiple choice options for money spent on jewellery in the last year start at £0-100.  I think there’s a huge difference between spending £5 or £100 on necklaces, but to be fair this method does make for a cleaner and easier filling-out process.

My total result from this one was 5.46 tonnes per year. It then tells me “You’re living as if we had 1.65 planets, but we only have 1“. Considering the well-known statistic is that most Europeans live as if we had 3 planets, this isn’t too bad.

I think this was my favourite calculator over all.


From this brief look at carbon calculators, I will conclude that they’re a good way to raise awareness of the issue of carbon emissions, but they should only be used as a rough gauge.  I’m very dubious about the actual accuracy of the estimations given as most of them don’t even list sources. The first one as I’ve said was wildly out, and as a Government endorsed site this was a bit shocking. (But only a bit…). I think calculators would be a good tool for making our society more sustainable if they had a little bit of improvement. The concept is a good one but there’s definitely work to be done.


One thought on “Carbon Calculators – An Evaluation

  1. A lot of online carbon calculators are unfortunately not very good. I have published a peer-reviewed article in the International Journal of Greenhouse Gas Control evaluating the 15 most popular calculators on the internet (http://www.sciencedirect.com/science/article/pii/S1750583613002168). My analysis documents significant shortcomings of many of the calculators. To remedy this situation, CarbonStory was created as a free calculator meeting all 13 evidence-based principles identified in the research (https://www.carbonstory.org/).


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