Carbon Pricing Calculators — Carbon Tax, ETS, Internal Price & MACC

How carbon gets priced: tax, ETS, or a price you set

Three mechanisms put a price on a tonne, and they differ in who sets the number, who owes it, and what happens when you emit less. Knowing which applies to you is the whole basis of using any tool here — the mechanism decides the maths.

A carbon tax fixes the price and lets emissions land where they will. A government sets a rate per tonne, defines which fuels and sectors it covers, and you owe the rate on what you emit. The cost is predictable; the environmental outcome is not.

An emissions trading scheme does the reverse. It fixes the quantity — a cap on total allowances — and lets the market discover the price. You hold a position: allowances allocated or bought against emissions you must surrender at the end of a compliance period. Emit less than you hold and you have a surplus to sell; emit more and you buy the shortfall at whatever the market asks. The environmental outcome is bounded; the cost is not.

An internal carbon price is neither. No authority levies it and no market clears it — the organisation sets a number and applies it to its own decisions, either as a shadow price used in appraisal or as a real internal fee moved between budgets. It exists to change choices before an external price arrives, which is why the right level is a strategy question rather than a lookup.

Which price applies to you? Start here

Start from the mechanism you are exposed to, or the decision you are trying to make.

Pick your carbon pricing calculator

Know the mechanism? Go straight to the calculator.

Which calculator do I need?

Each tool sits under a different mechanism, and the mechanism decides what a valid answer looks like. This table maps the tool to what it prices and the basis it applies.

What each calculator covers

Two of these tools price an obligation someone else imposes; two price a decision you make. The distinction matters, because only the first two produce a number you can be billed for.

Carbon tax & ETS liability by jurisdiction

The carbon tax liability calculator estimates what you owe where a statutory price applies, working from covered emissions and the jurisdiction’s rate (methodology). The hard part is rarely the multiplication — it is coverage. Every scheme defines its own scope: which fuels, which sectors, which thresholds, and which exemptions or rebates apply. Two companies with identical emissions in the same country can owe very different amounts because one falls inside a covered sector and the other does not. Rates also move on their own schedules, so the vintage of the rate matters as much as its level. Schemes such as Singapore’s carbon tax illustrate the pattern: a headline rate means little until you know what it covers and when it steps up.

EU ETS allowance position

The EU ETS allowance calculator works out where you stand in a trading scheme rather than what you owe in tax (methodology). Under the EU ETS, covered installations receive or buy allowances and must surrender one for every tonne of verified emissions in a compliance period. The output is a position — surplus or deficit — not a bill: a surplus can be banked or sold, a deficit must be bought at market. Free allocation complicates it further, since part of your allowances may arrive without purchase, which means your exposure is the gap between allocation and emissions rather than emissions themselves. The UK ETS runs on the same logic under separate rules.

Setting an internal or shadow carbon price

The internal carbon price calculator applies a price you choose to the emissions in scope, so the real question it forces is what the number is for (methodology). A shadow price is used in appraisal only — projects are tested against it so carbon-intensive options look as expensive as they eventually will be, without money moving. An internal fee is charged for real, moving budget between business units and funding abatement. The two demand different levels: a shadow price is usually set against an anticipated future external price, while a fee has to be low enough to be tolerable and high enough to change behaviour. Setting one without deciding which it is produces a number that does nothing.

Ranking abatement with a MACC

The marginal abatement cost calculator ranks measures by net cost per tonne abated, producing the curve that shows which tonnes are cheap and which are expensive (methodology). Its value is the ordering: some measures pay for themselves and sit below the line, and finding those before you buy compensation is the point. Its limits deserve the same attention. A MACC treats measures as independent when they interact — insulate a building and the heat pump you also modelled abates less. It compresses one-off capital and recurring savings into a single figure, and it says nothing about how long a measure takes to deliver. Read as a ranking heuristic it is invaluable; read as a plan it will mislead.

Why carbon prices aren’t comparable across countries

The most common question this cluster attracts is which country has the highest carbon price, and it is close to unanswerable as asked. The World Bank Carbon Pricing Dashboard is the authoritative source for rates across jurisdictions, and its own conventions explain why a naive league table misleads.

Four things break comparison. Coverage differs: a high rate applied to a narrow slice of the economy can cost less in aggregate than a modest rate applied broadly. Exemptions and free allocation mean the headline rate is often not what a covered emitter effectively pays. Vintage matters: dashboard rates are captured as an annual snapshot on a fixed date, so a scheme that stepped up the week after is shown at its old level until the next update. And currency conversion puts every rate in US dollars at a point-in-time exchange rate, so part of any gap between two countries is foreign exchange rather than climate policy.

The practitioner’s position is to compare exposure, not rates. What a carbon price costs your organisation depends on which of your emissions are covered, what allocation or exemption you receive, and the rate’s vintage — which is what the liability calculator asks for, and why it returns a figure for your defined scope rather than a national headline.

How the numbers are built

These calculators differ from most on the site in that their inputs are policy parameters rather than physical emission factors. A tax rate, an allocation rule, a compliance deadline — each is set by a jurisdiction and changes on a legislative schedule rather than a scientific one. Rates and scheme parameters are versioned in the MasterBrain data layer like every other value here, so a figure carries the vintage it was calculated on, and each calculator has a matching methodology page setting out its assumptions and coverage boundaries.

The four tools map onto the four ways a tonne of carbon gets a price — the mechanism decides what the number means and who sets it:

Two consequences follow. First, a carbon pricing figure has a shelf life: an estimate computed against last year’s rate is not wrong so much as out of date, which is why the vintage travels with the number and why a liability should be recomputed at each reporting cycle rather than carried forward. Second, the emissions you feed in decide everything downstream. Every tool here takes a footprint as its input, so exposure inherits whatever boundary and completeness the underlying inventory carries, including the AR6 GWP-100 basis corporate reporting defaults to. A liability computed on a partial inventory is a precise answer to the wrong question.

Where a scheme sets an explicit rate, that rate is read live from the data layer at MasterBrain v2026.110 — a representative spread, from among the world’s highest carbon taxes to among its lowest:

From price to decision

Pricing carbon is only useful if it changes something. The natural sequence is to establish exposure, rank what abatement costs, fund the measures that beat the price, and only then consider what to do with the remainder. That is why the abatement curve sits in this cluster rather than a separate one: the price and the response belong to the same decision.

Where that decision leads depends on what you find. Measures that cost less per tonne than your carbon price are self-funding and belong in the plan that a target formalises — the net-zero and science-based target cluster covers setting and stress-testing that trajectory. For the tonnes that remain expensive to abate, compensation is a separate question with its own accounting rules, and the offsets, credits and removals cluster covers what a credit costs and whether it stands up — noting that buying a credit never reduces the emissions your inventory reports or your tax liability. The footprint all of this rests on comes from the corporate GHG inventory and accounting cluster. Companies importing into the EU or UK also face a border carbon price under the CBAM regime, which is priced with its own tools in the disclosure cluster. The full carbon calculator directory covers the source-level tools an inventory draws on.