Carbon Offset, Credit & Removal (CDR) Calculators

Offsets, removals and avoided emissions are three different things

Most confusion in the voluntary carbon market comes from one word covering three claims. Getting them apart is the whole basis of using any tool on this page, because they are priced differently, governed differently, and reported differently.

An offset funds an emission reduction somewhere else — a project that avoids emissions that would otherwise have happened, such as protecting a forest from clearing or replacing a coal plant with renewables. The atmosphere is no better off than the counterfactual; it is simply worse off less. A removal is different in kind: it takes carbon dioxide out of the air and stores it, in trees, soil, rock or a geological reservoir. And avoided emissions — sometimes marketed as “Scope 4” — are the savings your product or service enables for a customer, which is a claim about someone else’s footprint, not a credit at all.

The practical consequence is that a tonne is not a tonne. A cheap avoidance credit and a durable engineered removal both retire as “one tonne of CO₂e”, but they represent very different climate outcomes and cost very differently. The buyer’s real question is not the price per tonne but what the tonne actually is.

Pricing, qualifying, or accounting for a project? Start here

The tools here answer three different questions. What would compensation cost? Does a project or credit stand up as a claim? And how do avoided emissions or value-chain interventions get accounted, given they never touch your inventory total?

Pick your offset, credit or removal calculator

Know what you need? Go straight to the calculator.

Which calculator do I need?

Each tool sits under a different framework and answers a different question. This table maps the tool to the claim it supports and the standard that governs it.

What each calculator covers

These tools span buying, generating and accounting for credits. What connects them is that none produces a number that belongs inside your inventory total — they price, qualify or attribute compensation that sits beside it.

Pricing offsets by project type

The carbon offset cost calculator prices what compensating a given volume would cost, and the reason it asks for project type first is that project type is the dominant variable (methodology). Credits from cookstove or forest-protection projects, renewable-energy projects and engineered removals occupy different price tiers entirely, because they differ in how hard the reduction is to achieve, how confidently it can be measured, and how long it lasts. A quoted market average across all project types is close to meaningless for a buyer — the useful number is the price for the kind of credit that actually supports the claim you intend to make.

Engineered & nature-based removals — durability is the axis

The carbon removal (CDR) calculator prices removals across the pathways in the market: nature-based storage in forests and soils, biochar, bioenergy with carbon capture and storage, direct air capture, and enhanced rock weathering. The variable that sorts them is durability — how long the carbon stays put. A forest stores carbon for as long as it stands and can be lost to fire, disease or a change of ownership; carbon mineralised in rock or injected into geology is measured in millennia. Price tracks durability closely, which is the trade-off a buyer is really making: a large volume of reversible storage, or a small volume of permanent storage, for the same spend. Where a removal neutralises a residual under a net-zero target, durability is not a preference but a requirement.

Insetting vs offsetting — the one that touches your inventory

The insetting vs offsetting calculator compares two uses of the same abatement budget (methodology). Offsetting buys a credit from a project outside your value chain; insetting funds a reduction inside it — a supplier switching fuel, an agricultural practice change in your own sourcing region. The accounting difference is decisive and is the reason this calculator exists: an inset reduces emissions within your reporting boundary, so it shows up as a genuine cut in your Scope 3; an offset sits outside the boundary and does not. If the goal is a lower reported footprint or a science-based target, insetting is the only one of the two that moves the number.

Avoided emissions — why “Scope 4” is not a scope

The avoided emissions calculator quantifies the savings a product or service enables for its user, against a reference scenario of what they would otherwise have used, following WBCSD’s avoided emissions guidance (methodology). The informal label “Scope 4” is misleading: it is not a fourth scope, not part of the GHG Protocol’s scope architecture, and never added to or subtracted from your inventory. Those savings occur in someone else’s footprint. Reported honestly and alongside your own emissions, it is a legitimate and useful claim about a product’s climate value; presented as a deduction from your total, it is a straightforward accounting error.

Quantifying a crediting project (ISO 14064-2)

The ISO 14064-2 project calculator works from the project side rather than the buyer side: it quantifies the reductions or removals a project generates against its baseline scenario, under the international project-accounting standard (methodology). The hard part is never the arithmetic — it is the baseline. A credit is the difference between what happened and a counterfactual of what would have happened otherwise, so the credibility of every credit rests on whether that counterfactual is defensible. This is the same question the quality frameworks below ask from the buyer’s side.

What makes a credit credible

A credit is a claim about a counterfactual, which is why the voluntary market has spent years building integrity frameworks rather than just registries. The ICVCM Core Carbon Principles set the threshold criteria a credit should meet, and the VCMI Claims Code of Practice governs what a buyer may then say about it. The two halves matter together: a high-quality credit can still be described dishonestly.

Underneath the frameworks, three questions decide whether a credit is worth anything. Additionality — would the reduction have happened anyway? If the project was commercially viable regardless, the credit funds nothing new. Permanence — will the carbon stay stored, and what happens if it does not? Biological storage carries reversal risk that geological storage largely does not. Leakage — did the emission simply move? Protecting one forest achieves little if clearing shifts to the next valley.

Registries operationalise these questions through their methodologies: Verra’s Verified Carbon Standard and the Gold Standard are the largest voluntary programmes, the Woodland Carbon Code governs UK woodland creation projects, and CORSIA is the compliance scheme for international aviation. Which registry issued a credit, under which methodology and vintage, tells you more about its quality than its price does — and the honest position is that this remains a market where diligence is the buyer’s job, not the registry’s alone.

How the numbers are built

The pricing tools here differ from the rest of the site in an important way: they output a cost, not an emission. There is no single emission factor behind an offset price, because the voluntary carbon market is not a commodity market with one clearing price. Price depends on project type, registry and methodology, vintage, co-benefits, volume and the moment you buy. Any figure these calculators return is a market estimate for a defined project type at a stated vintage, versioned in the MasterBrain data layer like every other value on the site, and it should be treated as an indication for budgeting rather than a quote.

The four things you can do about a residual tonne are not interchangeable, and the accounting treatment differs sharply — this is the distinction the top of the page turns on:

The quantification tools rest on firmer ground. An ISO 14064-2 project figure and a WBCSD avoided-emissions figure are both scenario comparisons — project against baseline, solution against reference — so their reliability comes from the defensibility of the counterfactual rather than from a factor’s precision. Each calculator states the scenario and assumptions it used, and each methodology page sets out the boundaries. Where a figure depends on a global warming potential, the AR6 GWP-100 basis that corporate reporting defaults to applies here as elsewhere.

The single axis that most separates a credible credit from a weak one is durability — how long the carbon stays out of the atmosphere. These durability scores are read live from the data layer at MasterBrain v2026.110 (Oxford Offsetting Principles, 0–3):

Where this sits in your climate plan

Compensation is the last step, not the first. The sequence every credible framework asks for is the same: measure the footprint, cut what can be cut, and only then address what is left. Buying credits before the measurement and reduction work is done is how organisations end up paying for compensation they did not need, against a total they could not defend.

That is also why the tools here sit outside the reduction path rather than on it. Under a science-based target, offsets do not count toward the required cuts — the net-zero and science-based target cluster covers what does, and where removals legitimately neutralise a residual. The footprint those decisions rest on comes from the corporate GHG inventory and accounting cluster. Once measurement and reduction are underway, the calculators here tell you what compensating the remainder would cost and whether the credits stand up. The full carbon calculator directory covers the source-level tools an inventory draws on.