The 8 Best Carbon Accounting Software Tools in 2026

Carbon accounting software measures a company's Scope 1, 2 and 3 emissions and turns them into numbers you can report to customers, investors and regulators. For UK businesses in 2026 the pressure usually comes from one of four places: SECR reporting, a large customer asking for supplier emissions data, a public-sector tender that needs a Carbon Reduction Plan under PPN 006, or a B Corp or SBTi commitment.

We compared eight platforms that UK companies shortlist most often. For each one we cover who it suits, how it prices and how much expert help comes with it. We checked every vendor's own website and G2 profile in October 2026.

A note before you read: we make Zevero, one of the tools on this list, and we have put it first. We have tried to describe every platform fairly. If you want to see how we compare on your own data, join our live group demo or check our pricing first.

The best carbon accounting software at a glance

• Zevero: UK mid-market companies that want software and a sustainability expert in one plan. From £1,500 a year (Zevero Lite, Scope 1 and 2). G2 4.7 from 18 reviews.
• Seedling: UK SMEs and mid-sized firms up to 2,000 staff, with a free starter tier. G2 5.0 from 11 reviews.
• Greenly: SMEs to enterprises across Europe, now joining with Normative. Quote-only. G2 4.7 from 27 reviews.
• Sweep: enterprises and financial institutions with complex group structures. Quote-only. G2 4.8 from 4 reviews.
• Watershed: large enterprises with in-house climate teams. Quote-only. G2 4.5 from 25 reviews.
• Persefoni: companies that want a free entry tier and investor-grade disclosure later. G2 4.8 from 11 reviews.
• Sage Earth: small businesses already on Sage Accounting. Included at no extra cost for Sage Accounting customers.
• Microsoft Dynamics 365 Sustainability: large organisations already on Microsoft. Licensed through Microsoft or a partner.

How to choose carbon accounting software

Start with the reason you need it, because that decides which features matter.

• A customer has asked for your emissions. You need a credible Scope 1, 2 and 3 footprint fast, in a format your customer accepts. Ask each vendor how long a first footprint takes and who checks the methodology.
• You report under SECR or bid for public contracts. Check the platform produces SECR-ready figures and a Carbon Reduction Plan that meets PPN 006.
• You have set, or plan to set, a science-based target. Look for target-setting, reduction modelling and year-on-year tracking, not only a one-off footprint.
• You sell physical products. Ask whether the platform can produce product carbon footprints or EPDs as well as a company footprint.
• You have no sustainability team. Ask how much expert time is included and whether it is a named person. This often matters more than any feature.

For a full checklist, read the questions to ask when evaluating carbon accounting software.

1. Zevero

Best for: UK mid-market companies that want accurate Scope 1, 2 and 3 data and an expert to help act on it.

Zevero combines carbon accounting software with sustainability experts who work on your account. The platform uses AI to match your business data to more than 200,000 emission factors across 7 global databases, then an expert reviews the methodology with you.

Why it stands out: every plan includes full Scope 3 across all 15 categories, target setting, unlimited users and guided implementation. The level of expert involvement rises with each tier, from periodic reviews to an embedded partner who prepares your data and builds your net zero roadmap. Zevero also produces product carbon footprints, EPDs, B Corp audits and AI-assisted ESG reports.

Pricing: Zevero Lite covers Scope 1 and 2 from £1,500 a year. Essential, Leading and Premium plans are quoted. Add-ons are priced from £500 per product footprint. See all plans.

Things to know:

• Main plans are quote-based, so you will need a short call for a price
• Best suited to companies that want expert support; teams that only want self-serve software may not use the full service

2. Seedling

Best for: UK SMEs and mid-sized firms up to 2,000 employees.

Seedling is a UK carbon accounting platform with a named expert on each account. It covers SECR, Carbon Reduction Plans for PPN 006 and NHS supplier requirements.

Why it stands out: a free Starter tier lets small teams begin without a contract, and paid tiers add SBTi target-setting and net zero roadmap modelling.

Pricing: Starter is free. Core and Advanced are quote-only.

3. Greenly

Best for: SMEs to enterprises across Europe that want broad automation.

Greenly serves around 4,000 clients and says the UK makes up about 30% of its revenue. It supports UK SRS, SECR and UK ETS reporting, and offers an AI assistant called EcoPilot and product life cycle assessments.

Why it stands out: breadth of automation and a large client base. In September 2026 Greenly announced it is joining with Normative, the Swedish carbon accounting platform. Both brands will run separately in the short term, so check what the combination means for your contract before signing.

Pricing: quote-only, varying by sector.

4. Sweep

Best for: enterprises, financial institutions and groups with many business units.

Sweep focuses on assigning emissions data and responsibility across teams and subsidiaries. It has a UK SRS module and counts SSE and Rothschild & Co among its customers.

Why it stands out: strong governance for complex organisations and an AI assistant, Sweepy. Sweep also lists a Starter package alongside its enterprise plans.

Pricing: quote-only.

5. Watershed

Best for: large enterprises with in-house climate teams.

Watershed works with global companies such as Walmart and BlackRock. Its platform uses AI agents to clean data, map emission factors and draft reports.

Why it stands out: depth for enterprise-scale programmes, including regulatory reporting and decarbonisation planning across many sites and countries.

Pricing: quote-only. Generally priced for large organisations rather than mid-market teams.

6. Persefoni

Best for: companies that want to start free and grow into investor-grade disclosure.

Persefoni offers a free Pro tier for one user at companies with low to medium complexity, and an Advanced tier for enterprises. It has a London office and an SECR report add-on.

Why it stands out: the free tier is one of the easiest ways to produce a first footprint yourself. Advanced adds AI data ingestion and supplier tools for Scope 3.

Pricing: Pro is free for one user. Advanced is quote-only.

7. Sage Earth

Best for: small businesses already using Sage Accounting.

Sage Earth calculates emissions from your accounting transactions, using UK spend-based data.

Why it stands out: it is included for Sage Accounting customers at no extra cost, and AI sorts transactions into emission categories automatically.

Things to know: spend-based estimates are a good starting point, but customers and auditors asking for detailed Scope 3 data may need activity-based figures.

8. Microsoft Dynamics 365 Sustainability

Best for: large organisations already running Microsoft systems.

Formerly Microsoft Sustainability Manager and part of Microsoft Cloud for Sustainability, the product now sits under Dynamics 365. It includes DEFRA emission factors and connects to other Microsoft data sources.

Why it stands out: tight integration with the Microsoft stack, with Copilot features in preview.

Pricing: needs a tenant licence plus per-user licences, bought through a Microsoft Enterprise Agreement or a partner. Expect to need IT or partner support to implement it.

Other platforms worth knowing

Plan A was acquired by Diginex in January 2026 and focuses on software, business services, fleet and fashion. Ecologi combines Scope 1 to 3 measurement with funding climate projects, and names SECR and PPN 006 among the requirements it supports.

Which carbon accounting software is right for you?

If you want to measure for free and do the work yourself, start with Persefoni's Pro tier, Seedling's Starter tier or Sage Earth if you use Sage. If you are a large enterprise with a climate team, Watershed, Sweep and Microsoft are built for that scale.

If you are a UK mid-market business that needs credible Scope 3 data for customers, tenders or targets, and you do not have a full sustainability team, Zevero's mix of software and experts is designed for you. Book a demo, join the next live group demo or see pricing.