Carbon footprint calculators – what to ask to help you choose

Knowing the carbon footprint of your farm is becoming increasingly important. Some processors and buyers are already asking for footprints as part of their environmental obligations, and the number is likely to increase. A carbon footprint can show the greenhouse gas (GHG) emissions hotspots in a business and where improvements should be made. Additionally, being able to show positive change in your footprint has the potential to bring extra income in the future, such as through the carbon markets.

There are many carbon footprint calculators out there. You should make sure that you pick the right tool for you. Below, we have provided some important questions you should ask when choosing a carbon footprint calculator tool.

It is important that a consistent record of your footprint over time can be made, starting with a baseline, so it is best to pick one tool and stick with it. If you do change tools, you should redo all historical assessments in the new tool, as results from different tools aren’t comparable.

These questions determine whether the tool is right for you and your farm.

• Does my buyer/supply chain require a specific tool?
  • Check if your supply chain specifies a particular tool
• Does it cover everything my farm produces?
  • Some tools cover all crops and livestock species, while others focus on a specific sector
• What levels of footprint are provided?
  • Tools may provide footprinting at whole-farm, enterprise, production-system and product levels
• How easy is the data-entry process – do I need support?
  • Often, you can enter your own data and written guidance is provided. Some tools require more detailed information, while others have a simplified option. Some tools also offer to help with the data entry, often for a fee
• How much does it cost?
  • There are several free options available. These may be more basic, with other features available (such as assistance or benchmarking) for a cost
• Can I make comparisons?
  • This could be ‘what if’ scenarios, reports over time, or benchmarking. See if this service is provided – and if it costs extra. Benchmarks might be against national averages, against a group, or against your farm’s theoretical best result
• Does it include carbon sequestration?
  • Some tools also include carbon sequestration – this could be biomass sequestration, such as woodland and hedgerows, or sequestration of soil carbon

These questions help ensure you have the best data possible – and will be important to those who might want to see the data as proof of your footprint. 

• Does it adhere to a set standard?
  • A calculator should be based on robust science and data. Adherence to a set standard is a quick way to show this. Officially recognised standards for carbon footprinting exist, but not all calculators use them. These standards include ISO14064 and ISO14067, the Greenhouse Gas Protocol, and SBTi FLAG guidance. The PAS 2050:2011 standard has been previously recommended, but this is now considered outdated per Defra’s calculator harmonisation work (published early 2024) Additionally, the IPCC has set methodology to account for greenhouse gas emissions, and some calculators follow this methodology. This could be either at tier 1 (basic) or tier 2 (intermediate)
• How does it cover methane and nitrous oxide emissions?
  • These are the two main greenhouse gases from agriculture. In order to be comparable with carbon dioxide emissions, the amounts are routinely calculated as carbon dioxide equivalents (CO₂e) using the global warming potential over 100 years. Some tools are now dual reporting, using GWP* for methane to better take account of its relatively short-lived nature in the atmosphere
• Does it regularly update and improve?
  • A static tool that doesn’t get updated doesn’t just miss out on gaining new features but also may not reflect the latest scientific data, e.g. on emissions factors
• Does it link to assessments of other environmental impacts?
  • A number of the tools are also linking to water and biodiversity metrics

These are some of the companies with popular carbon tools, listed alphabetically: Agrecalc, Cool Farm Alliance, Farm Carbon Toolkit, Solagro and Trinity Agtech.

As a starting point, a comparison of three of these tools is provided below. There are also numerous other tools available. It is worth taking the time to explore the options to identify the tool that will best suit your needs.

Table 1. Comparison of three popular carbon calculators. Last updated January 2024.

Currently, there is not a lot of harmony between calculators – even those following the same standards will have subtle variations in their calculations which lead to different results. In 2023, Defra commissioned a report to identify where the main differences between results occurred and how these could be improved. The calculators used were: Agrecalc (from Agrecalc Ltd), Cool Farm Tool (the Cool Farm Alliance), Carbon Footprint tool (Eggcase Ltd), Farm Carbon Calculator (Farm Carbon Toolkit), Sandy (Trinity Agtech’s natural capital navigator) and The Farm Carbon Calculator (SolAgro)

As of February 2024, two companies have published responses to the report with regards to their tools: Agrecalc (read it here) and Trinity Agtech (read it here).

What does this mean for farmers?

Due to the variation in calculations, results between different calculators can’t be compared. Therefore, to build a multi-year baseline, or show changes over time, all your farm’s footprints must be done in the same tool.