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    QHSEtech
    Updated 26 September 2026
    Carbon Accounting Buyer's Guide

    Carbon Accounting Software: Inventory and Supplier-Data Scope

    Choose the inventory workflow before choosing a reporting dashboard. Compare how each candidate links activity records, supplier data and calculation assumptions to a reviewed output, then establish which applications and services the quote actually includes.

    Jump to the 18 products

    Editorial responsibility: Dimitris Mitsios (Founder of The QHSE Standard; product marketing at Tekmon) · Tekmon pays for sponsored placements on this site (disclosure) · How pages are made · LinkedIn

    Official-source research reviewed 19 September 2026, with product evidence dates below. Buyer-fit judgments and proposed demonstrations are editorial, not hands-on tests. Compare the wider ESG reporting shortlist.

    On this page (9 sections)

    Carbon accounting products that meet the rule

    Where this guide has its own note on what to evaluate, the card shows it; otherwise it shows the record's carbon or GHG capability with its source. File imports and cloud APIs do not demonstrate disconnected operation; free entry access does not establish the cost of a complete reporting programme.

    Tekmon pays for a sponsored placement (above); its place in this list follows the same rule as every entry. How lists are ordered

    Same rule for every product: tagged “Carbon Accounting”, “Carbon Management”, “Scope 3 Emissions”, “Scope 3” or “Emissions Reporting”, with a sourced carbon inventory or GHG calculation capability in its record, or one the vendor stated to us, labelled as vendor-stated. 18 qualify; the first 8 are shown, then the other 10.

    Also meet the rule, in the same order (10)

    Carbon accounting scope and pricing comparison
    ProductPublished priceFree trialOffline workflow
    GreenlyNoNot establishedNot classified
    NormativeNoNot establishedNot classified
    PersefoniNoNot establishedNot classified
    Plan ANoNot establishedNot classified
    SweepNoNot establishedNot classified

    Status labels from each profile's sourced record; open the profile for the evidence and dates.

    The table shows the first 5 products of the list, in the same order; every profile carries the same fields.

    Separate four decisions in the carbon workflow

    StageBuyer evidence to requestAcceptance question
    Inventory boundaryEntities, period, activities, exclusions and named data ownersCan the reviewer explain which records belong in this inventory?
    CalculationInput, unit conversion, method, factor source and dataset versionCan a second reviewer reproduce a material result?
    Supplier evidenceSupplier identity, period, boundary, original source and any estimateDoes this record fit the calculation, and what remains uncertain?
    DisclosureReviewed values, narrative, permissions, output format and correction historyCan the reporting team approve and reproduce the issued output?

    Reading the list, and the decisions that change the number

    The rule currently admits 18 products to the list: 10 with documented carbon or greenhouse gas scope, 8 with conditional scope and 0 resting on the vendor's own statement. 4 of the cards include a note written for this guide. Treat the count as a measure of documentation, not of capability. Admission shows that a record names carbon or greenhouse gas work with a source, and says nothing about the quality of the factors, the supplier data or the audit trail behind a figure.

    Before comparing products, fix the four choices that change an inventory more than the choice of software does. The first is the consolidation approach: whether you report emissions from operations you control, from operations you have a financial interest in, or by equity share, because the same group gives different totals under each. The second is the Scope 2 method: location-based and market-based figures can differ widely, and a tool should be able to hold both. The third is the treatment of Scope 3, where a first estimate is usually built from spend multiplied by a factor and is later replaced with activity or supplier data. The fourth is the base year and the rule for recalculating it when the boundary or the method changes.

    A hypothetical example, with made-up factors that you should not reuse, shows why the replacement step matters. A company spends 2,000,000 currency units on a purchased material, and a spend-based factor of 0.30 kg CO2e per unit gives 600 tonnes. Purchasing records later show 400 tonnes of the material delivered, and a supplier-specific factor of 1.2 tonnes CO2e per tonne gives 480 tonnes. The inventory falls by 120 tonnes, or 20 percent, with no change in what the company did. A product that overwrites the earlier figure, or cannot say which basis a number rests on, makes the change look like a reduction. Ask to see both versions side by side with the factor, the unit and the date of each.

    How carbon inventories commonly go wrong

    Units are converted silently, so a quantity in litres is read as kilograms and the error appears only in review.
    The same purchase is counted twice, once in a spend-based category and again from a supplier survey.
    A factor library is updated and past results change without a visible note, so a reported year cannot be reproduced.
    Supplier names are matched loosely and one supplier's data lands on another.
    An estimate is accepted as actual data because nothing in the record separates the two.
    The reporting workspace receives values by upload and the link back to the calculation is lost, so a correction in the inventory never reaches the disclosure.

    Questions to put to each vendor in writing

    Which consolidation approaches and Scope 2 methods are supported in the quoted edition, and can both Scope 2 figures be kept? Which factor sources and versions are used, and what happens to an issued year when a factor is revised? How are spend-based estimates marked and replaced, and can the earlier basis be recovered? What is the supplier survey entitlement, how are non-responders handled and who reviews the answers? Which parts of the disclosure workflow are inside the quote and which sit in another application? Ask for each answer in writing and keep it with the quote, since a feature in a demonstration is not evidence for the package you would buy.

    Run a proposed three-part buyer demonstration

    1

    Import difficult records

    Bring a utility record, a procurement line and a duplicate with the wrong unit. Have the intended user identify the entity, period, rejected input and manual correction. Record the time and assistance required without treating the result as an industry benchmark.

    2

    Challenge a supplier estimate

    Use similar supplier names and a document with an incomplete reporting boundary. Inspect matching, source quality and the decision to retain an estimate or accept a replacement. Where supplier surveys depend on the plan, confirm that entitlement before relying on outreach.

    3

    Correct and hand off a result

    Trace a calculation into the required report, then correct the underlying input. Demonstrate the effect on the draft, retained history and review responsibility. If a separate reporting platform is the destination, name the applications, credentials and configured interfaces included in the quote.

    Request a quote for the complete workflow

    List users, entities, reporting years, activity volumes and supplier outreach scope.
    Separate software from onboarding, migration, expert review, factor licences and ongoing support.
    Name API or connector entitlement, SSO, report exports and the owner of failed-data reconciliation.
    Record currency, billing period, minimum commitment, renewal conditions and exit exports in the proposal.
    Request applicable security reports and their scope. Product logos and a public trust page do not replace your own review.

    Sources, methodology and limits

    104 sources, checked 26–29 Sep 2026

    The linked profiles distinguish vendor-documented scope from unverified plan entitlement. Software does not determine your legal reporting obligation, validate a target or guarantee independent assurance. For regulatory scoping, use the current CSRD guide.

    Our evaluation framework weighs functional depth 25%, usability and adoption 20%, implementation and TCO 15%, integrations and API 15%, security and trust 15%, and customer voice 10%. These are evaluation priorities, not calculated scores for this list.

    Workiva vs PersefoniScope 3 guideEnvironmental operations

    Record what the demonstration established

    Keep the observed result, unresolved question and commercial dependency together. Compare the same inventory and disclosure deliverable before negotiating a proposal.

    Build a carbon demo scorecard

    Software categories to explore

    Use this Process to define the work, then explore these software types. Confirm the exact workflow and module with each vendor.

    See all software categories

    Related guides

    Frequently Asked Questions

    Is carbon accounting the same as ESG reporting?
    No. A carbon inventory supports one part of a broader reporting programme. Specify both the calculation evidence and the destination disclosure workflow.
    Which candidate should a small team evaluate first?
    Start from the required outputs and the plan that covers them; team size alone does not establish fit, and a free or single-user entry plan may not include every user, export or control you need. In our catalogue, the 18 products that meet this guide's rule (a matching tag or allowed primary category, plus a sourced carbon inventory or GHG calculation capability or one the vendor stated to us) are Greenly, Normative, Persefoni, Plan A, Sweep and 13 more, in documented-match order (see the list on this page). That order reflects documentation, not quality; no product is recommended.
    Are supplier-specific numbers automatically better?
    No. Review the source, period, boundary and calculation method before replacing an estimate. An apparently precise number can still be unsuitable for your inventory.
    Does a reporting platform include carbon accounting in every subscription?
    Do not assume it. A named carbon offering can be a separate purchase, and a reporting platform can also receive externally calculated carbon data through configured interfaces; name the carbon application in the quote.
    Can carbon accounting products work offline?
    Each profile records its own offline evidence. Test interrupted work and recovery; an upload template does not prove an offline application.
    Does a ready-made report guarantee compliance?
    No. Your team must determine applicable obligations, assess completeness and authorise the report. External assurance remains a separate engagement.