Should you reduce or offset your emissions?

Offsetting is easy to buy and hard to get right. Reducing is harder to do but certain. This page explains why the order matters, what is left to offset once you have cut what you can, and how to describe it honestly.

It is part of our carbon footprint section. For practical cuts, see how to reduce your carbon footprint.

Reduce first, then offset

• Footprint: 10.0 t
• After cuts: 6.0 t
• Offset: 6.0 t

Example only, not a measured household. Credits cover what’s left after reductions — not the whole footprint.

Why reducing comes first

A tonne you don’t emit is a sure thing. A carbon credit is a claim about a tonne avoided or removed somewhere else^{Source 6}, and its value depends on whether the project really delivered it. Our guide to whether carbon offsets work summarises what independent studies have found about that.

The main guidelines agree on the order:

• Oxford Offsetting Principles. The first principle is to prioritise reducing your direct and indirect emissions to minimise the need for offsetting, noting that reducing has co-benefits and that the supply of high-quality credits is limited^{Source 2}.
• VCMI. Carbon credits must be used in addition to, and not to delay or displace, urgent and deep decarbonisation^{Source 3}.
• SBTi. Credits must be reported separately from a company’s emissions inventory and do not count as reductions towards its near-term or long-term targets^{Source 1}.

The mitigation hierarchy

These rules add up to a simple hierarchy, from most to least important:

1. 1

   Step 1: Measure

   Work out your footprint and its biggest sources, so you know what you are reducing.

2. 2

   Step 2: Avoid and reduce

   Cut the largest sources first: travel, home energy, diet and what you buy, or for a company its scope 1, 2 and 3 emissions.

3. 3

   Step 3: Neutralise what remains

   Balance residual emissions with carbon removals that store carbon for a long time.

4. 4

   Step 4: Go beyond

   Optionally fund extra climate action outside your own footprint, without counting it as a cut.

The SBTi’s net-zero standard has the same structure: near-term and long-term reduction targets, neutralisation of residual emissions, and “beyond value chain mitigation” for action outside the company’s value chain, which can include avoiding, reducing or removing emissions^{Source 1}.

What are residual emissions?

Residual emissions are what is left after you have cut everything you reasonably can. The SBTi notes that most companies will reduce emissions by at least 90% through their long-term targets, but that not every company can decarbonise completely^{Source 1}. Those remaining emissions must be neutralised by removing carbon from the atmosphere and storing it permanently, and a company can’t claim net zero until it has done both^{Source 1}.

The Oxford Principles reach a similar end point. They ask organisations using credits to increase the share that comes from carbon removals, aiming for 100% removal credits by the global net zero date, 2050 at the latest^{Source 2}. See removal vs avoidance credits for the difference. Our guide to residual emissions goes into more detail.

For a person, the idea is the same, even without a formal target. Your residual footprint is what remains after the big changes in our reduction guide, such as living car-free, flying less, switching to renewable electricity and changing diet. Each of those had a median saving of between 0.8 and more than 1.7 tonnes of CO₂e a year in a review of 53 studies^{Source 5}.

When does offsetting make sense?

Buying credits is reasonable when:

• You have already cut what you can, and are paying for emissions you can’t yet avoid, such as a necessary flight.
• You are going beyond your own footprint, funding extra climate action on top of your reductions, as the SBTi’s beyond value chain mitigation allows^{Source 1}.
• You can check what you buy: a named project, a public registry and a retirement record.

It is not a good idea when it replaces cuts you could make, or when it lets you claim more than the credits can prove.

VCMI’s Claims Code ties corporate claims to the same order: a company sets short-term emission reduction targets, aligned with net zero by 2050, before buying high-quality credits from outside its value chain^{Source 4}. Its Silver, Gold and Platinum claims need credits equal to at least 10%, 50% and 100% of remaining emissions^{Source 3}.

Common mistakes

• Offsetting the whole footprint first. Buying credits for everything before cutting anything sizes the purchase on emissions you could have avoided, and leaves the real sources untouched.
• Treating credits as reductions. A credit funds action somewhere else; your own footprint is unchanged. Company standards keep the two in separate columns for this reason^{Source 1}.
• Buying once and stopping. Your footprint recurs every year. Measure again, cut again, and size the next purchase on what is left.
• Choosing on price alone. Very cheap credits can come from older projects or weaker methods. Check the registry record and the project type before you pay.
• Ignoring the type of credit. For residual emissions over the long term, the Oxford Principles point towards removals with durable storage rather than avoidance credits^{Source 2}.

How many credits do you need?

Size your purchase on what is left after cutting, not on your original footprint. In the example above, a footprint cut from 10 to 6 tonnes needs credits for 6 tonnes, not 10. The credits needed calculator turns your remaining tonnes into a number of credits, and one credit stands for one tonne of CO₂e^{Source 6}.