Sustainable Wells carbon footprint calculator

<download link for the spreadsheet coming soon . . . >


Summary instructions

  1. Download and open the spreadsheet.
  2. Fill in or select a dropdown option from the grey cells for each of the questions that is applicable to you.
  3. Your total will be shown at the top along with the UK average and aims for sustainable living.

Full instructions

This is a calculator to help people who are interested to see how big their carbon footprint is and where it comes from. It is based on personal consumption. Things we have direct control over. It looks at the detail of these everyday things, so you can see where your efforts are best placed to have the biggest impact. National figures including those given by the UK government are often based on national production. These are often under estimates for developed countries that import many goods, meaning they export much of their CO2 (and other) pollution to countries with lower environmental standards, where financial costs of production are lower. They often also exclude emissions from international travel.

The calculator estimates the footprint of your personal life in the form of greenhouse effect (tonnes of Carbon Dioxide equivalent, CO2e) and compares this to typical UK and sustainable amounts. It is designed to work out your personal footprint and doesn’t include things you do for work or any offsetting you may do (e.g. paid services, tree planting, renewables, etc.), just your personal footprint.

The calculator works by you choosing your units from the drop-down where it says ‘Please choose’ in the ‘Units’ column, and entering a number in the grey cell in the ‘Answers’ column. Please enter numbers as figures rather than text (e.g. ‘3’, not ‘three’) and answer for the based on the previous 12 months unless the units specifically say otherwise. Some questions are multiple choice and you just need to pick the most suitable answer from the dropdown list. To be more accurate use amounts rather than costs where possible (e.g. an answer in ‘kWh’ will be more accurate than an approximation from one in ‘£’). If a question doesn’t apply to you, leave it blank or enter ‘0’. Be as honest as possible. 

Once you have selected your units and entered value, a multiplier and its units will appear to the right, and to the right of this, your footprint for this particular item in kilograms of CO2 equivalent (kgCO2e). To the right of this are notes to help you find the answer or explain the outcome. These are summarised at the top under ‘Current’ in tonnes of CO2e – think of it like pounds and thousands. Further details and sources can be found on the ‘Figures’ tab. When you have completed the question below you can set yourself a target under ‘Your aim’ at the top and monitor your progress by copying previous years totals to the top right under ‘Previous years’.

The ‘Other’ row and cell in grey in the summary at the top of this sheet under ‘You’ can be used to add in anything the spreadsheet doesn’t cover. Much of the structure and information has come from two great books on the subject: Carbon Detox and How Bad Are Bananas, with gaps filled and figures updated.

Please feel free to share and improve this calculator. If you discover an error or make an improvement please let us know at



The original objective of this calculator was to help people who want to do something about climate change see where there greatest opportunities lie, so that they can use their time effectively by knowing what the big issues are and to save them from being overwhelmed by all the smaller ones (‘I want to do something, what can I do?’ seems to be a common question). Basically a step beyond any footprint calculator I could find as they were either not specific enough (e.g. generic questions and outputs based on large averages) or didn’t include everything (embedded, overseas, indirect or whole groups of emissions)

It’s largely based around the method used in ‘Carbon Detox’ by George Marshall (2007) with the figures updated and options expanded (and references him and others where appropriate)

The colours of the graphs to fit with Zero Carbon Britain as much as possible (alignment isn’t perfect as they take a top down, national approach and look at food and energy separately)

The spreadsheet is set up with a tab for general use and a second with all the multiplier figures so that they can easily be updated as things change with time without changing the front end. I was thinking this might even have benefits for management of a website

The aim is not for it to necessarily stay as a spreadsheet, but be as user friendly as possible, i.e. probably a website, possibly an app, possibly something else. Please get in touch ( if you can help with this

It is pretty accurate and a step up from many other calculators, but it is still very much an estimate (most figures and all the generally large ones have been double checked and compared against other calculators). No doubt there will be small errors left but as these should be similar through out, it should still serve its purpose of pointing you in the right direction of what to focus on. That’s not to say it can’t or won’t be improved.

The greatest potential area for improvement is probably the food section, as this is the one that has been most difficult to double check. The main issues is that presently two people who have pretty much the same diet, would come out as having the same footprint regardless of if one were to eat twice as much as the other (and presumably have about twice the footprint in reality). I feel like it needs a ‘how much do you weigh’ box. . . . . It’s already more or less got a ‘how much do you earn one’!!

One major caveat, is that it is a CO2e calculator and falls into the usual trap of being carbon-centric, i.e. looks at things as carbon equivalent and on a 100 year basis. In view that things are more pressing, it would be nice to make a ’20 / 100 year’ button but it for a future revision

Similarly It would be nice to give a footprint in terms of GHa too. This was the original plan but has been put on hold to get something that can be used. Quite a bit has been done towards this already. It’s probably the next big improvement and will make it a bit less carbon focused. Other planned future improvements are noted at the top of the second tab