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The Carbon Calculator is designed for users who want to understand carbon accounting and take action. It is based on the basic Excel tool provided in the GHG Protocol Corporate Value Chain (Scope 3) Standard e‑learning course, publicly available in 2025 on the GHG Protocol website.

The main goal of the carbon tool is to produce carbon inventories that are compliant with carbon accounting standards, actionable, secure, and auditable. The tool is also designed to operate with high energy efficiency. The calculator is deliberately designed as a flexible and methodology-driven tool, rather than being limited to predefined use cases. It fully preserves the scoping and mapping phases of a carbon inventory, recognizing them as essential steps for building understanding, transparency, and confidence in the results. By guiding users through mapping-based calculations, the calculator enables more robust carbon accounting and empowers organizations to trust their numbers and take meaningful, informed action.

Preliminary requirements

Following the GHG Protocol approach, the users shall define as early as possible the purpose of the carbon inventory, for instance what they are willing to change or improve in their organization. The calculation tool shall be used together with carbon mapping and carbon scoping. Scoping is the process of defining the boundaries of your carbon footprint—activities, sites, entities, and operations you want to address.

Mapping is the process of identifying which activities generate greenhouse gas emissions and how they connect to your operations. If your goal is to change your strategy, you may not need an ultra-detailed carbon calculation (the mapping can be macro), but you do need to see the whole picture (the scope should be as broad as possible). Once you have a rough idea of the main sources of emissions, the critical step is deciding what to do. You may decide that emission-intensive operations are business-critical and that you want to change your business model. Or you may decide that emission-intensive operations are business-critical and cannot be eliminated. It is entirely up to you. The calculator does not judge. It is here to help you make decisions on numbers you trust and understand. Additionally, users should have a basic understanding of arithmetic. We recommend not assigning responsibility for your carbon footprint to someone without this knowledge.

How does it work?

The Carbon Calculator helps consolidate carbon inventory information with varying levels of sensitivity. Its structure enables users to easily manage and interpret the data used to calculate the carbon footprint of a product or an organization. While inspired by the GHG Protocol Standards, the calculator can also be used to produce carbon footprints compliant with ISO 14064, ISO 14067, or other relevant industry specific standards.

The tool consists of:
• Calculation tabs: This is the main tool, where GHG emission sources are listed and the carbon footprint is calculated.
• Audit tables: These are automatically generated and cannot be edited by the user (except for the comment sections). They serve internal and external audit purposes and allow you to check at a glance the assumptions behind your carbon inventory, the precision of your carbon footprint (which you can judge from the type of data used in your calculation), and provide an overview of the emission factors used.
• Calculation rules: These are used to manage operations on measures (numbers with units).
• Databases: include separate databases for variable storage, enabling multiple purpose-specific data stores with different trust levels