27 Jan 2022

Are carbon calculators effective in measuring event emissions?

Maya Mhatre

There are numerous carbon calculators for both personal and business use. They’re a great way to get a snapshot of how your activities drive emissions. 

The WWF calculator 

This looks at considerations such as how much meat you consume, how much food you waste, whether food is locally sourced, your most often used mode of transport, how many flights you’ve taken and their distance, whether you offset flights, how many tech gadgets you buy, how many clothing and beauty products you buy, etc. 

It gives you a total emissions score in tonnes and splits this into segments related to travel, stuff, food and home so you know your worst performing areas and tips to improve them.

It’s a good starting point if you’ve never considered your emissions. It keeps it simple and introduces you to areas to be mindful of. For example:

Carbon Footprint Small Business Calculator

Only the small business version is free but it has a fair amount of detail. It lets you drill down into specific areas of the business to understand emissions across building, flights, car & van, vehicle fuel and bus & rail. 

It splits out each section with emissions per activity so bus, taxi, rail or electricity, gas and even the allocation for those working from home. It also summaries by impact stream and gives you an average footprint per employee. This could be a nice benchmark to set objectives against if you are focusing on company emissions (as opposed to event).

Looking at event emissions more specifically you will need calculators that go into more detail. 

My Climate Event Calculator

Another free calculator that helps you track event emissions specifically. It goes into a lot of detail which is great but also means you will need a lot of data including number of participants, sqm of heated or air conditioned areas, number of people arriving by car, public transport, plane, number of nights accommodation, number of beverages consumed, power consumption, material usage, materials used, transported weight, etc. However if you don’t have any of these data points you can leave it blank and continue the calculations without them.

It details mobility, accommodation, catering, energy, materials, transport and waste with an emissions metric per tonne applied per category. Again, a great starting point. However, it doesn’t split out the variables within each impact category and it doesn’t let you edit the categories to know if you reduce the number of nights accommodation by 15% for example, how this affects your total emissions. It’s a good basis to get an overview of your existing emissions however, if you don’t know this yet it’s definitely worth doing.

Greenhouse Gas Reporting: Government Conversion Factors (Condensed)

To go into more detail, whether that’s to be able to drill into each activity further or to be able to set reduction targets and play around with how the different inputs will affect your emissions, the best tool is using the conversion factors the government provides. These are updated annually and allow you to look at the type of vehicle used, whether the fuel is petrol, diesel, electric, hybrid, other forms of travel, accommodation by type and country, electricity, waste disposal, specific materials used and whether they are primary or even closed-loop in origin such as metals, clothing, food, compost, electrical items, types of plastic and paper and so much more. It also splits out the metrics into Scope 1, 2 and 3. 

You will need to download these. It has a lot of data variables so unsurprisingly is a large spreadsheet but it also gives pointers on how to use the document and examples.

Which do you follow?

This all depends on how much time you have available, the data you can access and where you are on your journey in terms of measuring and reducing. If you are not currently measuring any emissions, any one of these is a great starting point even measuring just your own personal emissions is hugely beneficial. If you want to start creating or furthering sustainability objectives for your business, the more detail you can go into the better, in which case the government metrics would be the best tool.

Worked example

If I want to see how much I can reduce my events footprint specifically through printed materials choices I can use the government conversion factors tool to work out some variations. 

First I need to know the existing associated emissions for 2000 copies of a 6 page A4 brochure.

Using print calculations, I know a 6 page A4 brochure on 170gsm = 31.5g.

If I produce 2,000 copies for an event this would weigh 63,000g.

We need to convert this to tonnes to use the government calculations and then multiply by the conversion factor for paper (919.4). So 0.063t x 919.4 = 57.92 kgCO2e or 0.06 tCO2e. These are the associated emissions in kg or tonnes.

Now we have a base measure, we can see how this changes when we shift certain variables by selecting different weights, quantities and stock and using the government conversion factors to see the calculations.

As you can see in the table below the related emissions vary depending on the changing circumstances. Notably, changing to closed loop recycled stock does not have as drastic a reduction as one might think, the better reductions are through reducing the material so either size, quantity or stock.




Weight in t


Emissions in kgCO2e





Primary paper


Reduce quantity




Primary paper


Reduce size




Primary paper


Change stock




Closed loop recycled paper (739.4)



Being able to understand what possible changes will make to your overall emissions is very useful when setting out your objectives and strategy. It’s all very well aiming to reduce electricity emissions or waste by 20% or event materials by 25% but without understanding how your current emissions are made up and which variables impact them you may be setting yourself up for a fall.

Continuing calculations - Join one of our Workshops

Either use a free calculator and plug in the variables you are considering so you can compare multiple calculations or use the conversion metrics to keep your own spreadsheet of results in a greater level of detail.

If you want further support, we use the government conversion factors as the basis of our Event Sustainability Workshops. These workshops are small, personalised, interactive groups held online over 3 sessions to help you understand how to measure and calculate your emissions and use the results to drive forward your sustainability strategy and objectives. Find out about upcoming dates here. These tend to sell out so book quickly so save your place soon or keep a look out for future sessions.

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