Best Carbon Accounting Software for B Corp Businesses: What to Look For in 2026

Quick Answer: B Lab's updated standards, which apply to all new applicants from March 2026, make carbon accounting a mandatory requirement for certification. You must measure Scope 1, 2, and 3 emissions in line with the GHG Protocol, set science-based reduction targets, and produce a Climate Transition Plan. Seedling, Plan A, Greenly, Ecologi Zero, and Hedgehog Carbon are all worth considering, depending on your team size and reporting needs.

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Tool	Best For	Standout Feature	Pricing
Seedling	B Corp applicants wanting software plus dedicated expert support	Built-in Climate Transition Plan report aligned to B Corp's Climate Action topic	Subscription pricing (see pricing page)
Plan A	Mid-to-large companies focused on decarbonisation	TÜV Rheinland-certified calculations with AI-assisted data mapping	Contact for pricing
Greenly	Teams wanting lifecycle analysis alongside GHG reporting	AI-powered anomaly detection for data quality control	Contact for pricing
Ecologi Zero	Businesses new to carbon accounting seeking a guided start	Footprinting tool with B Corp-aligned reporting outputs	Contact for pricing
Hedgehog Carbon Platform	Companies wanting a free entry point to Scope 1, 2, and 3 measurement	Free tier covering Scope 1, 2, and selected Scope 3 categories	Free tier available; Pro version contact for pricing

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Carbon accounting for B Corp is no longer optional. B Lab's updated global standards, which took effect for new applicants on 11 March 2026, require every certified business to measure and disclose a full GHG inventory, set a net-zero target, and produce a Climate Transition Plan. This article breaks down exactly what the new standards require and which software tools are built to help you meet them.

What Do the New B Corp Standards Require for Carbon Accounting?

B Lab's updated framework replaces the previous 80-point overall threshold with mandatory minimum scores across individual Impact Topics. The Climate Action topic is one of nine, and poor performance there can no longer be offset by high scores elsewhere.

For the Climate Action topic, B Lab requires three things:

For large businesses, independent verification of your GHG report is also required. You submit a copy of your most recent report, with signatures from an independent verifying party clearly marked.

If you are working toward B Corp certification and need to build your Climate Transition Plan, Seedling's platform covers all three requirements in one place.

The 5 Best Carbon Accounting Tools for B Corp Applicants

1. Seedling: Best for B Corp Applicants Wanting Software Plus Expert Guidance

What it does well: Seedling is built specifically for businesses that want accurate, GHG Protocol-aligned carbon accounting without it becoming a full-time job. The platform covers full Scope 1, 2, and 3 measurement, with tools like accounting integrations (Xero, Sage, QuickBooks), built-in employee and supplier surveys, and AI-assisted spend categorisation that reduces manual mapping. Measurement typically takes 2-4 weeks end-to-end, with under one day of your time overall.

What sets Seedling apart for B Corp applicants is the direct alignment between the platform and B Lab's requirements. Your GHG inventory, net-zero targets, and decarbonisation action plan all pull through automatically to populate a Climate Transition Plan report built to B Corp's standards. A dedicated account manager (SBTi-certified) guides you through the full process, from data collection to target setting to report sign-off.

Best for: Companies of up to around 2,000 employees, particularly those with lean or no sustainability teams, who need a credible, verifiable footprint and a B Corp-ready CTP without handing the whole process to a consultant.

Pricing: Subscription pricing. See the Seedling pricing page for current plans.

2. Plan A: Best for Mid-to-Large Companies Focused on Decarbonisation

What it does well: Plan A is a carbon management platform with a strong focus on decarbonisation strategy. Its calculations are TÜV Rheinland-certified and GHG Protocol-compliant, and the platform uses AI to guide data mapping, detect anomalies, and connect emissions data to reduction scenarios. Plan A is trusted by large organisations including BMW, Visa, and Alphabet, and it supports reporting for B Corp, CSRD, and SBTi.

Best for: Mid-to-large companies with sustainability teams who want a decarbonisation-first platform and need to manage complex data across multiple entities or reporting frameworks.

Where Seedling differs: Plan A is a strong fit for organisations with dedicated sustainability resource and complex reporting structures. Seedling is built for businesses where carbon accounting needs to be manageable alongside other responsibilities, with an efficient process, a dedicated expert, and clear subscription pricing rather than day-rate scope creep.

You can read more about how the two platforms compare on the Plan A alternatives page.

3. Greenly: Best for Teams Wanting Lifecycle Analysis Alongside GHG Reporting

What it does well: Greenly offers a full-scope carbon accounting platform with strong data quality features. Its AI-powered anomaly detection flags statistical errors during data collection, which helps sustainability teams maintain audit-ready accuracy. The platform also supports lifecycle assessments, supplier engagement aligned with SBTi and CBAM requirements, and trajectory builders for scenario analysis. Expert support is available via Q&A sessions and e-learning modules.

Best for: Sustainability teams that need lifecycle analysis capabilities alongside corporate GHG reporting, particularly those operating in product-heavy sectors where value chain emissions require detailed supplier data.

Where Seedling differs: Greenly is a strong choice for teams with the capacity to manage more detailed LCA workflows. Seedling is optimised for businesses that need a full-scope, GHG Protocol-aligned footprint and a B Corp-ready Climate Transition Plan delivered efficiently, with a dedicated expert doing the heavy lifting.

See how they compare on the Greenly alternatives page.

4. Ecologi Zero: Best for Businesses New to Carbon Accounting

What it does well: Ecologi is designed to simplify carbon accounting and provide insights for businesses at the start of their sustainability journey. The platform supports B Corp-aligned reporting outputs and has been used by B Corp-certified businesses including Remarkably, a creative consultancy that used Ecologi to quantify its carbon footprint for the first time. Ecologi's broader platform also connects businesses to verified climate projects.

Best for: Organisations new to carbon accounting that want a guided, accessible starting point, particularly those already engaged with Ecologi's wider platform.

Where Seedling differs: Ecologi is a good fit for businesses taking their first steps. Seedling is built for those who need a more detailed, activity-data-driven footprint (not just spend-based estimates), with independent assurance, SBTi-aligned target setting, and a dedicated expert to manage the process year-on-year.

5. Hedgehog Carbon Platform: Best for a Free Entry Point to Scope 1, 2, and 3 Measurement

What it does well: Hedgehog Carbon Platform offers a practical online tool for measuring, managing, and reducing CO2 emissions, with a free tier that covers Scope 1, 2, and selected Scope 3 categories including business travel and commuting. The Pro version provides advanced features and a more detailed emissions factor database. Hedgehog also supports SBTi registration and provides guidance on carbon accounting and reporting for B Corp compliance. The platform is GHG Protocol-compliant and supports CSRD and B Corp reporting requirements.

Best for: Businesses that want to start measuring emissions without an upfront cost, or those exploring carbon accounting before committing to a full platform.

Where Seedling differs: Hedgehog is a strong entry-level option. Seedling is designed for businesses that need a fully assured, activity-data-led footprint with expert support, year-on-year consistency, and outputs that hold up to independent verification, all within a single subscription.

How We Chose These Tools

Every tool in this list was selected based on four criteria relevant to B Corp applicants specifically:

Seedling is the only tool on this list purpose-built around the B Corp Climate Action topic, with a CTP report template aligned to B Lab's requirements and a dedicated carbon expert included as standard.

FAQs

Q: Does B Corp require carbon accounting?

A: Yes. Under B Lab's updated standards, which apply to all new applicants from March 2026, every certified business must measure and publicly disclose a full GHG emissions footprint covering Scopes 1, 2, and 3, set a science-based reduction target, and produce a Climate Transition Plan. Carbon accounting is now a mandatory element of the Climate Action topic.

Q: What is a B Corp carbon footprint?

A: A B Corp carbon footprint is a full GHG inventory covering Scope 1 (direct emissions from owned operations), Scope 2 (indirect emissions from purchased energy), and Scope 3 (value chain emissions). It must be measured in line with the GHG Protocol and reported annually, including total emissions per scope in metric tonnes of CO2 equivalent and CO2 intensity per unit of revenue.

Q: Do B Corps need independent verification of their carbon footprint?

A: Yes. B Lab requires that GHG reports submitted as part of the Climate Action topic have been independently verified. You submit a copy of your most recent CO2 report with signatures from an independent verifying party clearly marked. Seedling's outputs are assured to align with the GHG Protocol, and the platform supports ISO 14064 verification for businesses that need third-party sign-off.

Q: What is a Climate Transition Plan for B Corp?

A: A Climate Transition Plan (CTP) documents a business's emissions baseline, science-based reduction targets, and the specific actions it is taking to reduce emissions over time. Under B Lab's updated standards, a CTP is a required output of the Climate Action topic. Seedling's platform automatically populates a CTP report from your emissions data and target-setting work, using a template aligned to B Lab's requirements.

Q: Can I use carbon offsetting to meet B Corp's climate requirements?

A: No. B Lab's updated standards are explicit that carbon offsetting does not count toward the reduction targets required under the Climate Action topic. Businesses must demonstrate actual emissions reductions. Offsetting may still play a role in a broader climate strategy, but it cannot substitute for measured, verified reductions.

About Seedling

Seedling is carbon accounting software with dedicated expert support, built for businesses that want a credible, full-scope footprint without enterprise-level complexity. The platform covers Scope 1, 2, and 3 measurement aligned with the GHG Protocol, decarbonisation planning and target setting, and one-click reporting for frameworks including B Corp, SECR, PPN 006, EcoVadis, and ISO. A dedicated carbon expert guides every client through the full process, from data collection to Climate Transition Plan sign-off. Setup typically takes 2-4 weeks, with under one day of client time overall. Book a demo to see how Seedling can help you meet B Corp's new Climate Action requirements.