What is carbon intensity?

Quick Answer: Carbon intensity is a measure of how much greenhouse gas a company, product, or activity emits relative to a unit of output, such as revenue, energy produced, or goods manufactured. It is expressed as emissions per unit (for example, kgCO2e per £1,000 of revenue) and allows organisations to track emissions efficiency over time, even as the business grows or changes in size.

What is carbon intensity?

Carbon intensity is a normalised emissions metric. Rather than reporting total greenhouse gas output as a single absolute figure, it expresses emissions relative to a meaningful unit of business activity.

Common denominators include revenue, headcount, square metres of floor space, units produced, or energy consumed. The choice of denominator depends on what makes the most sense for a given business or sector.

For example, a logistics company might measure kgCO2e per tonne-kilometre delivered. A professional services firm might use tCO2e per £1 million of revenue. Both approaches produce a ratio that can be tracked year on year.

Why does carbon intensity matter for measuring progress?

Absolute emissions figures tell you how much a company emits in total. Carbon intensity tells you how efficiently it emits relative to what it produces or earns.

This distinction matters because businesses grow. A company that doubles in size will almost certainly see its absolute emissions rise, even if it has genuinely improved its environmental performance. Carbon intensity accounts for that growth, making it possible to compare performance fairly across different periods or between organisations of different sizes.

Investors, procurement teams, and sustainability frameworks increasingly ask for both metrics. Absolute reductions remain the goal, but intensity figures provide important context, particularly for growing businesses making the case that their emissions efficiency is improving.

Carbon intensity is also a core component of science-based target setting. The Science Based Targets initiative (SBTi) allows certain sectors to set intensity-based targets rather than absolute targets, where the nature of the business makes absolute reductions harder to commit to in isolation.

How is carbon intensity calculated?

The calculation itself is straightforward:

Carbon intensity = Total greenhouse gas emissions (CO2e) / Chosen activity metric

The more demanding part is getting the emissions figure accurate and complete. A carbon intensity ratio is only as reliable as the footprint data behind it. If scope 3 emissions are excluded, or if the methodology is inconsistent year on year, the intensity figure becomes difficult to interpret or compare.

This is why the denominator choice and the emissions boundary need to be defined clearly and held constant. Switching from revenue to headcount between reporting periods, or changing which emission sources are included, makes trend analysis unreliable.

For organisations using Seedling, the underlying footprint is built to GHG Protocol standards across scopes 1, 2, and 3, which means the emissions data feeding into any intensity calculation is consistent, documented, and assured.

What is the difference between carbon intensity and absolute emissions?

These two metrics answer different questions:

• Absolute emissions measure total greenhouse gas output in a given period, expressed in tCO2e. This is the figure that matters most for the climate: the atmosphere responds to total emissions, not ratios.
• Carbon intensity measures emissions per unit of output. This is the figure that matters most for benchmarking efficiency, setting performance targets, and comparing businesses of different scales.

Neither metric replaces the other. A company could improve its carbon intensity while its absolute emissions rise, if growth outpaces efficiency gains. Equally, absolute emissions could fall due to a drop in output rather than genuine decarbonisation. Reporting both gives a clearer picture of what is actually happening.

Most credible sustainability frameworks, including the GHG Protocol and SBTi guidance, recommend disclosing both figures for this reason.

How carbon intensity fits into a decarbonisation plan

Tracking carbon intensity over time helps identify where a business is becoming more or less efficient in its emissions, and where intervention will have the most impact.

For example, if a company's revenue grows by 20% but its carbon intensity per £1,000 of revenue falls by 15%, that signals genuine progress in decoupling emissions from growth. If intensity stays flat or rises, it suggests that growth is driving emissions at the same rate or faster, and that operational changes are needed.

Intensity metrics work best when paired with a clear understanding of which emission sources are driving the figure. A high intensity ratio is more useful as a starting point for action than as a standalone data point.