BeZero or Calyx: how do carbon credit ratings differ?

Both now use the same eight-letter scale from AAA to D for the chance a credit delivers one tonne. BeZero rates carbon efficacy only and publishes headline ratings free. Calyx gives separate GHG, SDG and environmental and social risk ratings, by vintage. Neither rating is a verification or a registry approval.

BeZero Carbon

• Rates the likelihood a credit achieves one tonne of CO2e avoided or removed. Co-benefits and fraud risk are outside the rating unless they affect that likelihood.
• Headline ratings on issued credits are public and free. Pre-issuance ratings stay private unless agreed.
• Payment does not depend on the grade; no MRV consulting, no trading and no advice on which credits to buy.
• Every rating is approved unanimously by a ratings committee.

Calyx Global

• GHG rating on four risks aligned with the ICVCM Core Carbon Principles: additionality, over-crediting, permanence and overlapping claims.
• Separate SDG ratings on a +1 to +5 scale, and an environmental and social risk screen across 10 areas.
• Ratings by vintage, so a project's grade can change over time.
• Does not sell ratings to project developers and does not trade credits. Developers can ask to join the rating queue at no charge.

Reading the two side by side

The letters match, but Calyx scores four ICVCM-aligned risks while BeZero gives one view of carbon efficacy, so the same letter can rest on different reasons. Compare the reasons behind a rating, not just the letter.

Not covered here

Sylvera and MSCI also rate credits. Read their own methodology pages before comparing their grades with these two.

What Senseible does here

A rating agency reads the project's evidence. Senseible keeps that evidence in order: the records behind each tonne and the verifier evidence pack an accredited verifier reviews.

• What a rating letter means
• Do you need a rating?
• Carbon removal for buyers
• What to check before buying

Sources: BeZero Carbon, The BeZero Carbon Rating definition and rating scale (21 December 2023), BeZero Carbon, Independent carbon ratings (8 April 2024, editor's note October 2026), Calyx Global, Our approach: GHG, SDG and environmental and social risk ratings, Calyx Global, A new GHG rating scale (21 January 2025), Calyx Global, Calyx Ratings: free tiered ratings and who pays

Last reviewed 2026-11-02.