Top 5 Carbon Accounting Software in the UK (2026)

For UK SMEs and mid-market companies with formal regulatory obligations (SECR, PPN 06/21, NHS Net Zero or ESOS), Climatise is the strongest platform. It is the only platform in this top 5 that natively generates the actual disclosure documents (not just GHG figures), covers full GHG-Protocol Scope 1, 2 and 3, and pairs the inventory with a built-in reduction-planning module. Greenly is the strongest broader EU SME option. Seedling and Alectro are the best lighter UK SME trackers for organisations without formal regulatory obligations. Sage Earth is a fit for UK micro-businesses already on Sage Accounting that want a quick spend-based baseline.

Climatise generates the full SECR disclosure, including the Directors’ Report narrative, intensity metric framing, energy efficiency action commentary and intensity ratios, ready for Companies House. Greenly, Seedling, Alectro and Sage Earth can produce the underlying Scope 1 and Scope 2 figures but do not natively assemble the Directors’ Report narrative.

Climatise is the only platform in this top 5 that natively generates a PPN 06/21-compliant Carbon Reduction Plan (Scope 1, 2 and required Scope 3 categories 4, 5, 6, 7 and 9, a Net Zero by 2050 commitment, environmental management measures and a director-signed declaration) ready to upload with central-government bids over £5m.

Climatise. The platform has a dedicated NHS Net Zero workflow covering the published roadmap milestones: PPN 06/21 alignment for contracts over £5m by 2027, Scope 3 supplier engagement and product-level emissions. The other 4 platforms in this top 5 produce underlying GHG figures but not the NHS-specific submission workflow.

All five platforms in this ranking are GHG-Protocol aligned across Scope 1, Scope 2 and Scope 3, but depth varies. Climatise covers all 15 Scope 3 categories where material, with activity-based primary data and automated supplier engagement. Greenly and Seedling cover Scope 1, 2 and 3 with hybrid activity and spend approaches. Alectro and Sage Earth lean spend-based for Scope 3 with lighter category depth, which is acceptable for screening but not for formal disclosure or assurance.

Climatise has reduction planning built in: SBTi-aligned target setting, a costed initiative roadmap with abatement curves and year-on-year progress tracking against the baseline. Greenly and Seedling offer target setting and progress tracking but with less depth on the initiative side. Alectro and Sage Earth do not provide reduction planning natively; users typically move to a more capable platform once measurement gives way to planning as the priority.

Export your historical inventory as CSV or Excel from the incumbent platform, plus any supporting documents (utility bills, supplier returns, methodology log). Climatise’s onboarding team, and equivalent teams at Greenly and Seedling, reconcile the categorisations to the GHG Protocol structure, apply the latest factors and preserve the historic baseline for SECR continuity. Typical migration runs 2 to 4 weeks within a standard 6 to 8 week onboarding.

Climatise compiles this buyer guide. We score every platform, including ourselves, against the same eight criteria listed in the Selection criteria section. The scoring draws on each vendor’s public website, published case studies, documented UK regulatory outputs and our own direct experience working alongside or migrating customers from each tool. We refresh this ranking quarterly; the last refresh date is shown on the page. This is a top 5 view. The full top 10 is published at /best-carbon-accounting-software/uk-sme.