How To Calculate Your Carbon Footprint?


In this article we discuss 5 simple steps to help you calculate your carbon footprint without using a consultant or losing your sense of humor.

Following these steps will ensure that you get a consistent and reliable measure of your environmental impact.

At the end of the article we have provided some useful links to online carbon footprint calculators so that you can get started today.

But first it is important to understand some definitions.

Carbon Footprint Definition and Important Notes

A carbon footprint refers to the greenhouse gas emissions that are caused, either directly or indirectly, by a person, organisation, event, service or product.

When we say carbon, what we actually mean is carbon dioxide (CO2). However a carbon footprint takes into account more than just CO2 emissions. It captures all key greenhouse gas emissions: Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs) and Sulphur hexafluoride (SF6).

A carbon footprint expresses all of these greenhouse gas (GHG) emissions as a carbon dioxide equivalent – you will see the term CO2e. To find out the difference between CO2 and CO2e, have a look at this article.

All you need to remember is that your organisation’s carbon footprint should be expressed as CO2e, capturing all GHG emissions. Fortunately most carbon footprint calculators and conversion factors use CO2e as standard.

Still with us? Good.

The second thing to remember is that there are two types of carbon footprints.

1. Organisational carbon footprint – which expresses all the emissions from your organisation, including those in your value chain (or what we term scope 3 – we’ll cover this below)

2. Product carbon footprint – these are the emissions that occur over the life-cycle of a product, from manufacture to use and disposal.

This page deals specifically with organisational carbon footprinting. If you are interested in product carbon footprints we suggest visiting the Carbon Trust page on this topic.

Now that we have covered those important points, lets look at the 5 things you need to know to measure your carbon footprint.


Step 1. Define the boundary for your carbon footprint

Boundary is an important concept in carbon footprinting as it sets the constraints for consistent year-on-year assessment.

The point of measuring a carbon footprint is to reduce so it is important that you get this right.

Failing to define the carbon footprint boundary can inhibit comparisons against benchmarks / other organisations and could also undermine meaningful monitoring of performance.

There are three types of boundaries:

Type 1: Operational control

This approach draws a boundary around the elements that your company has operational control over. Using this approach means that everything that you company operates gets captured in the carbon footprint. This can extend into the supply chain if an organisation has sufficient operational control over suppliers.

Type 2: Financial control

This approach covers all elements that your business financially controls. Often this excludes elements which your company may operate but not financially control and therefore using this approach can result in a smaller carbon footprint.

Type 3: Equity control

This approach includes all elements that your company owns. If your company has part ownership then the proportion ownership is used to calculate the relevant carbon footprint attributable to that company. Of course there can be circumstances where your company operates and financially controls an asset but does not own the asset. In such a scenario these elements are excluded from the carbon footprint when using the equity approach

Our recommendation: Unless your organisation has a very complex business structure we recommend that you use an operational control approach


Step 2. Decide which emissions will be included under scope

Scope refers to the emission types captured in a carbon footprint. The scope of an organisation’s carbon footprint also breaks down into three components.


Source: New Zealand Business Council for Sustainable Development

Scope 1 emissions:

These cover all direct emission sources. These are emissions from assets that are either owned by your company ( i.e. fleet vehicle emissions from the consumption of fuel) or emissions produced through an on-site activity (i.e. emissions from the burning of natural gas in a company’s boiler)

Scope 2 emissions:

Scope 2 covers all indirect emissions or more specifically emissions derived from the production of purchased electricity. Here your company hasn’t actually produced the emissions associated with electricity generation but due to the consumption of electricity to power lights, equipment etc. we can say that your organisation is indirectly responsible for these emissions.

Scope 3 emissions:

Finally scope 3 covers all other indirect emissions which are not as a result of the consumption of purchased electricity. This includes a wide array of emission sources including waste, consumables, staff commute, supply chain emissions,water use etc.

Our Recommendation: At a minimum your organisation should capture scope 1 (onsite gas boiler emissions, car / fleet fuel consumption) and scope 2 emissions (electricity usage).


Step 3. Define your carbon footprint period

A carbon footprint is typically measured across an annual period. When choosing your period for measurement it is best to think of other reporting cycles which can be used as the set time-frame.

Many companies like to measure their carbon footprint against their financial reporting year. Other companies measure their carbon footprint against the calendar year.

Our Recommendation: Choose an annual period which takes advantage of existing reporting structures.


Step 4. Use a practical approach to collect annual data

Once you have defined your boundary and the type of emissions you are going to capture, you’ll then need to collect data on all elements that you are going to measure carbon emissions for (i.e. electricity and gas usage, vehicle mileage, waste volume etc.)

Data is often stored in odd places and formats. Most people get very frustrated trying to find all the required data that needs to be captured for a carbon footprint. We recommend keeping things as practical as possible.

Here are some top tips you can use

Tip 1: Annualise partial data

Data should be for an annual period. If you can’t get complete annual data you will have to use what you know about a sample of data to annualise your information.

For example, if you know that you used 1,000 litres of petrol for your fleet vehicles for the first six months of your carbon footprint period then you could extrapolate that you will use 2,000 litres over the year.

Note, be careful of seasonal or business fluctuations. Your vehicles may drive a lot more during the Christmas busy season which would distort the results if you don’t correct for this.

Tip 2: Use proxies where you don’t have primary data

The format of the data can also come in many shapes and forms. Sticking with fleet vehicles as an example, you may not know how much fuel you have consumed. Indeed you may not know how many miles your vehicles have driven. You may only know how much you spent.

If you don’t have primary data (i.e. litres consumed, kWh used etc.) you will have to convert your secondary data (miles driven, electricity spend etc.) into a primary data.

This can be done by using proxies – miles per gallon, cost per kWh etc.

Tip 3: Use intelligent estimation

The last port of call if you cannot get real data is to use estimation.

Here the best approach is to look at benchmarks (e.g. kWh per square foot for a particular office type) or basic knowledge of your operations (e.g. average trip is x km and we do 10 deliveries a day, therefore…).

Note, estimation should be used as a last resort and always stated in any published result.


Step 5. Calculate footprint

After you have collected all your relevant annual data the task is then relatively simple.

You need to use a carbon footprint calculator or carbon conversion factors to calculate your organisational carbon footprint.

There are many carbon footprint calculators on the internet that can be used for free. It is important that you check that the calculator you choose follows internationally recognised methods for carbon footprinting and uses emission factors which are relevant for your organisations country. Here are three calculators that we recommend.

If you are in the US this carbon footprint calculator from the University of California, Berkeley is excellent

For UK readers we recommend this carbon footprint calculator (you have to register to use it), or if you want to do it yourself using conversion factors we recommend these.

For all other readers we recommend ClimateCare’s calculator.

Interested in how you can reduce your carbon footprint? Definitely read this article

About the Author Staff Writer

Our writers come from all over the world, but one thing unites them - their passion for sustainability.

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1 comment
Teklal Mahato says May 1, 2021

Nice article

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