As more organisations begin to measure and manage their emissions, the number of carbon accounting tools available has grown quickly. This has created a new challenge. Businesses are no longer just deciding whether to measure emissions; they are also choosing the right tool in an increasingly crowded market.
At Sustainable Business Ventures, we spoke with a range of providers, including Notch, Small99, 51toCarbonZero, Sage Earth, and TrackZero, to better understand how these tools are designed, where they differ, and what businesses should consider when selecting a platform. The aim was not to rank or endorse, but to provide clarity and support better decision-making.
A fast-moving market
The tools reviewed span from early entrants launched in 2020 to platforms introduced as recently as 2024. This reflects how quickly the space is evolving, with many tools still actively building out their capabilities.
The key insight is that this is a fast-moving space where tools are still developing, and businesses should expect ongoing improvements rather than fully mature solutions.
Different tools for different users
There is no one-size-fits-all solution. Some tools are designed for accessibility, enabling in-house teams with no prior GHG expertise to get started quickly, often with limited data. This is particularly relevant for smaller businesses that need a starting point rather than a perfect dataset.
Others are built for more complex organisations, supporting enterprise-level Scope 3 analysis across supply chains and more detailed reporting needs. A growing number of platforms now sit between these two, supporting both internal teams and consultants and enabling larger organisations to engage SME suppliers across their value chains.
This highlights that choosing the right tool depends on your size, data maturity, and internal capability, rather than just features.
Strong alignment on standards
All tools align with the GHG Protocol and Science-Based Targets initiative, with many also referencing ISO 14064. Scope 1 and Scope 2 emissions are consistently covered, and all tools include some level of Scope 3.
Scope 3 is where carbon accounting tools start to differ
However, the depth of Scope 3 coverage varies. Around 60% of tools report full coverage, while 40% focus on selected categories. This reflects the complexity of value chain emissions, where data availability, supplier engagement, and methodology all influence what can realistically be measured.
In practice, many tools prioritise categories such as purchased goods and services, business travel, employee commuting, and upstream transportation, while more complex downstream categories are less consistently included.
For businesses, this highlights an important consideration. Two tools may appear similar at a high level, but the depth of Scope 3 coverage can vary significantly depending on the categories included and the data required. This is why Scope 3 coverage is a key differentiator, particularly for organisations with complex value chains.
Hybrid approaches are now common
Most tools now use a combination of methodologies rather than relying on a single approach. This reflects the reality that many organisations do not yet have access to complete primary data across all emissions categories.
Hybrid approaches are becoming the standard
Around 80% of tools use hybrid methodologies, combining spend-based and activity-based data to provide more flexible and practical calculations. A smaller proportion relies solely on spend-based approaches, typically as a starting point for organisations with limited data.
This shift highlights an important point. Carbon accounting is rarely a linear process, and the ability to move between estimation and more precise data over time is critical.
For businesses, this means that flexibility in methodology is essential, particularly for those earlier in their data journey or working across complex operations.
Data remains the biggest challenge
Across all responses, data quality and availability stand out as the central challenge. Tools manage this in different ways, from requiring complete datasets to allowing estimates that are clearly flagged and reported.
One area where this becomes particularly important is supplier data, which is a key component of Scope 3 emissions.
Supplier engagement is growing, but not yet standard
Around 60% of tools enable suppliers to upload their own data directly, while 40% do not currently offer this functionality. This reflects the growing recognition that accurate Scope 3 reporting depends on moving beyond estimates and engaging directly with value chain partners.
For businesses, this is an important consideration. Tools that support supplier engagement can help improve data quality over time, while those that rely solely on internal inputs may limit how far organisations can progress in their reporting.
This reinforces how a tool captures data across the value chain is just as important as how it calculates emissions.
Integration is still developing
While some tools offer integrations with finance and utility systems, others are still building these capabilities. This means that integration capability varies significantly and can affect how scalable and efficient a tool is over time.
Transparency is becoming essential
Most tools now provide access to assumptions and calculation logic, with some offering downloadable data or audit modules. This reflects a broader shift where transparency is becoming essential for credibility and trust.
Reporting is strong, tracking is evolving
Reporting capabilities are relatively well developed, with most tools able to generate outputs for clients, investors, and internal teams, often broken down by business unit or geography. Many also support frameworks such as SECR.
However, tracking progress over time is less consistent, with some tools still developing this functionality. This suggests that reporting is well established, but performance tracking is still evolving.
Pricing reflects a wide range of needs
Pricing varies widely, from low-cost or free options for SMEs to enterprise solutions ranging from £30,000 to £200,000 or more. This reflects differences in complexity, data depth, and level of support.
The key takeaway is that cost is closely tied to capability, rather than simply company size.
What this means for SMEs
For SMEs, the findings highlight both opportunities and limitations.
Many tools are increasingly designed with smaller businesses in mind, offering simple, cost-effective entry points and requiring limited data to get started. Some even provide free access or low monthly subscriptions, lowering the barrier to entry significantly.
However, this simplicity often comes with trade-offs. SME-focused tools may rely more heavily on estimates, provide less detailed Scope 3 coverage, or have fewer integrations. In some cases, they are designed as a starting point rather than a fully comprehensive solution.
At the same time, SMEs are becoming increasingly important within the value chains of larger organisations. Tools that enable supplier engagement and data sharing are helping SMEs play a more active role in Scope 3 reporting, even if they are not leading the process themselves.
The key takeaway is that SMEs do not need perfect data to begin, but they do need tools that match their capacity and allow them to improve over time.
What this means for businesses overall
This research highlights that there is no single best carbon accounting tool. Instead, the right choice depends on your organisation’s needs, including the complexity of your operations, the quality of your data, and how you plan to use the insights generated.
Ultimately, there is no single best tool; there is only the right tool for your context, and taking the time to understand these differences will lead to more effective and credible climate action.
Still unsure about carbon accounting tools? Get in touch for a complimentary 30-minute call.