What is a Carbon Calculator?

Putting Carbon Calculators to the test, and our top pick for small businesses

When you want to change anything in your business, it will only happen with a plan. But to have a plan, you need a starting point.

How will you know if you have reached your destination if you don’t know where you’ve started from?

Any goal we set for ourselves in our business needs to be measurable otherwise, how will we know when we’ve achieved it?

This holds true when it comes to reducing the impact our business has on the environment. To create a more sustainable business, we need to know what impact we are currently having, only then can we decide what changes to prioritise.

Whatever your views on greenhouse gas emissions and climate change, humans emit billions of tonnes of carbon into the atmosphere every year, which is huge in terms of pollution and impacts upon ecosystems and biodiversity.

This is where a Carbon Calculator can be a helpful tool to measure our current impact and decide which small changes will have the greatest effect.

Measuring your Carbon Footprint gives you a baseline from which to develop your plans to reduce your impact as a household and a business.

What is ‘Carbon’?

When using a carbon calculator to measure emissions, “carbon” typically refers to carbon dioxide (CO₂) and sometimes includes other greenhouse gases (GHGs) that are measured in terms of their carbon dioxide equivalent (CO₂e).

By measuring emissions in terms of “carbon,” carbon calculators provide a measurable way to consider our impact on the planet as businesses and individuals.

What is a Carbon Footprint?

Your carbon footprint is the amount of greenhouse gases, primarily carbon dioxide (CO₂), emitted directly or indirectly by human activities. It is measured in units of carbon dioxide equivalents (CO₂e), which standardizes different greenhouse gases based on their global warming potential.

Everything we buy, do, and eat has an impact on the world’s resources and Carbon Footprints are a way to quantify this impact in a measurable way. Although it has its limitations, it gives us data we can measure.

Reducing your carbon footprint reduces your environmental impact on the planet, and using fewer resources can contribute to cost savings for your business.

What is a Carbon Calculator?

A carbon calculator is a tool used to estimate an individual’s, household’s, or organisation’s carbon footprint, which is the total amount of greenhouse gases, primarily carbon dioxide (CO₂), emitted directly or indirectly by activities over a certain period. These calculators help users understand their impact on the environment and identify ways to reduce their carbon emissions.

Key Features of Carbon Calculators

Input Categories: Users typically provide information in several categories:

Energy Use: Electricity, natural gas, and heating oil consumption.
Transportation: Vehicle type, fuel efficiency, miles driven, and use of public transportation.
Waste: Amount of waste produced and recycling habits.
Food: Dietary choices, as different foods have varying carbon footprints.
Lifestyle and Consumption: Purchase habits, travel frequency, and other personal activities.

Calculation Methodology: The calculator uses standard emission factors to convert activity data into carbon emissions. Emission factors are averages that represent the emissions produced per unit of activity (e.g., kilograms of CO₂ per kilowatt-hour of electricity).
Output: The result is typically presented in metric tons or kilograms of CO₂ equivalent (CO₂e) per year. Some calculators provide detailed breakdowns by category to show which activities contribute most to the user’s carbon footprint.
Recommendations: Many carbon calculators offer suggestions for reducing emissions, such as using energy-efficient appliances, reducing car travel, or adopting a plant-based diet.

Putting Carbon Calculators to the test

A carbon calculator could be an app, a website, or a specially designed tool within an organisation.

To keep it simple, we’ve trawled through websites – so you don’t have to – and picked out 6 examples of Carbon Calculators, then put them to the test.

Here are the results:

Carbon Calculator	Pros	Cons	What’s our verdict?	Marks out of 10
Climate Hero: https://carbon-calculator.climatehero.org/	Some of the responses lack nuance with only ‘yes/no’ options. The advice is generic. The score at the end is your tonnes of carbon compared to international averages, which in itself is not a very useful metric. As a platform, their goal is to get money out of you to pay for carbon-offsetting projects, rather than to help you reduce your impact in other ways	This is a good choice for Sole Trades who don’t have premises, and the impact of their business depends on their individual lifestyle choices. However, it lacks the rigour and data analysis of some of the more complex calculators but is a good place to start to ease you into your impact reduction journey	More of a ‘fun’ tool than a data-driven one, but the questions are framed in such a way that it’s obvious where you could make changes to your lifestyle. The website also has lots of useful resources and tips, their focus being more on reducing your impact for the sake of nature and biodiversity than on fulfilling carbon reduction targets, which makes it far more accessible to the layman!	7/10
WWF WWF Footprint Calculator	Free tool. A trusted and credible charity with loads of useful resources and information on their website etc. Generates a clear report at the end and is suitable for measuring your own personal footprint, which will correlate with your business footprint if you are a sole trader. I really like the well-designed, appealing, and easy-to-navigate tips and resources to help you reduce your personal impact	Very simplistic and doesn’t include comprehensive business or spending data. Some of the questions are binary and lack nuance, sometimes you want to put in more detail and data but it doesn’t allow you to.	Free tool if you use accounting software the tool seems to connect automatically (although I haven’t tested this) which will populate the expenditure questions, potentially saving a lot of time and giving you a more accurate result	6/10 Best for lifestyle and household change
NatWest Carbon Planner Carbon Planner \| NatWest Business	You have to register and set up an account in multiple steps. If you don’t have the information, it won’t let you proceed (i.e.: kwh of electricity) so you will want comprehensive records and your utility bills to hand to use the tool. If you can’t connect your accounts software, you can’t proceed	It takes you through step-by-step. The profile saves as you go along so you don’t have to do it all in one sitting. Produces a report at the end with simple graphical information and percentages. Trusted government-backed resources aimed at businesses with lots of useful information on the website	The tool is aimed at larger businesses and is not very intuitive. You must include all the data in order to proceed. You must have a compatible accounting software in order to enter purchases. There are frustrating limitations to this tool and you get stuck in a loop if you can’t complete part of a section.	5/10
SME Climate Hub’s free tool: Start measuring – SME Climate Hub –	It takes you through step-by-step. The profile saves as you go along so you don’t have to do it all in one sitting. Produces a report at the end with simple graphical information and percentages. Trusted government-backed resources aimed at businesses with lots of useful information on the website	This is far more comprehensive than other tools. It is easy to work through but does require a lot of information about financial accounts, expenditures, inventory, etc. so will require comprehensive record-keeping in order to be accurate. If you have stock and inventory reporting in place already it will be more relevant. This is the best choice for a small business that needs a more comprehensive report. It allows you to continue even if you don’t have all the information to hand unlike some of the others.	This is far more comprehensive than other tools. It is easy to work through but does require a lot of information about financial accounts, expenditures, inventory, etc. so will require comprehensive record-keeping in order to be accurate. If you have stock and inventory reporting in place already it will be more relevant. This is the best choice for a small business that needs a more comprehensive report. It allows you to continue even if you don’t have all the information to hand unlike some of the others.	7/10 Best for businesses with staff and premises
CarbonFootprint.com carbonfootprint.com – Carbon Footprint Calculator	Not designed for businesses so may be too simplistic for a more complex business with staff, premises, etc. The transport questions are hard to answer (i.e.: mileage by bus, train, etc.). Questions around lifestyle ask for expenditure – hard to quantify without accurate records	Not designed for businesses so may be too simplistic for a more complex business with staff, premises, etc. The transport questions are hard to answer (i.e.: mileage by bus, train, etc.). Questions around lifestyle ask for expenditure – hard to quantify without accurate records	Free tool. You have to register, but once you have, the quiz suggests changes and pledges you can make, and then rewards you with points when you make progress. This gamified format makes it more accessible than others	5/10
Giki https://zero.giki.earth/	Not designed for businesses so may be too simplistic for a more complex business with staff, premises etc. Although the initial quiz is not comprehensive, the more you use it the more you refine it and the better results you get	Not designed for businesses so may be too simplistic for a more complex business with staff, premises, etc. Although the initial quiz is not comprehensive, the more you use it the more you refine it and the better results you get	Great tool with some useful resources around it. Although the initial quiz is too simplistic to give you an accurate footprint, the more you use it the more you refine your score, and the gamified format introduces an element of challenge.	8/10 Best for sole traders at the start of their sustainability journey

Conclusion

Living a more sustainable life and growing greener businesses is more than just knowing how many tonnes of carbon you produce. For many, the notion of a Carbon Footprint can be an abstract construct that is hard to get your head around. Although a useful metric to monitor your progress and choose changes that have the biggest impact, these tools come into their own once you have established your baseline and use the resources, guides, and tools associated with them. This is where you start to see the real impact of small changes – like wasting less food and energy, therefore saving money – or discovering new ways of working or opportunities you may not have identified otherwise.

Once you’ve measured your carbon footprint you can make a plan to reduce your impact.

There are a growing number of resources to help you reduce your carbon footprint. Here are a few further reading recommendations: