What is CO2e? Meaning, formula & why it matters
CO2e — carbon dioxide equivalent — is the standard unit for measuring the total climate impact of a product, service or activity. Here's what it means, how it's calculated, and how to read it.
Last updated: July 2026
In short
One common unit
CO2e converts every greenhouse gas into an equivalent amount of CO2 so you can compare them on one scale.
Simple formula
CO2e = mass of gas × its Global Warming Potential (GWP) over 100 years.
Standard for footprints
Used by the GHG Protocol, ISO 14067 and every credible product carbon footprint report.
CO2e meaning
CO2e stands for carbon dioxide equivalent. It expresses the warming impact of any greenhouse gas — methane, nitrous oxide, refrigerants and so on — as the amount of CO2 that would cause the same amount of warming over a defined period, typically 100 years.
The reason we need CO2e is that different greenhouse gases trap heat with wildly different intensities. Methane, for example, warms the atmosphere about 28 times more per kilogram than CO2 over a 100-year horizon. Rather than tracking each gas separately, CO2e rolls them into a single, comparable number.
You'll usually see CO2e reported in kilograms (kg CO2e) or tonnes (t CO2e). A carbon footprint expressed as "6.74 kg CO2e" means the product's lifecycle emissions have the same warming impact as releasing 6.74 kg of pure CO2 into the atmosphere.
How CO2e is calculated
Each greenhouse gas is assigned a Global Warming Potential (GWP) — a multiplier set by the IPCC that describes how much heat it traps relative to CO2. CO2e is simply:
Common GWP values (100-year, IPCC AR6)
| Gas | GWP (100-yr) | Typical source |
|---|---|---|
| Carbon dioxide (CO2) | 1 | Fossil fuel combustion |
| Methane (CH4) | ~28 | Livestock, landfill, gas leaks |
| Nitrous oxide (N2O) | ~273 | Fertiliser, industrial processes |
| HFC-134a (refrigerant) | ~1,530 | Air conditioning, cold chain |
| SF6 | ~25,200 | Electrical switchgear |
A worked example
Suppose a manufacturing process emits 10 kg of CO2, 0.5 kg of methane and 0.05 kg of nitrous oxide. The total CO2e is:
CO2e in a product carbon footprint
A product carbon footprint (PCF) sums the CO2e from every lifecycle stage: raw materials, manufacturing, transport, use and end-of-life. The final number — for example, "6.74 kg CO2e per unit" — is what appears on labels, ESG reports and tools like URLCarbon.
Reporting the total in CO2e (rather than separate lines for each gas) is required by the GHG Protocol Product Standard and ISO 14067 — the two most widely used frameworks for product-level carbon accounting.
What's a "good" CO2e number?
CO2e values only make sense within a category. A t-shirt and a laptop live on completely different scales. Use these rough benchmarks as a starting point:
| Product | Typical footprint |
|---|---|
| Cotton t-shirt | 5–10 kg CO2e |
| Pair of jeans | 15–25 kg CO2e |
| Smartphone | 40–80 kg CO2e |
| Laptop | 200–400 kg CO2e |
| 1 kg beef | ~60 kg CO2e |
| 1 kg oat milk | ~0.9 kg CO2e |
FAQs
Is CO2e the same as CO2?
No. CO2 is one specific gas. CO2e is a combined figure that includes CO2 plus every other greenhouse gas, each converted using its GWP.
Why use a 100-year time horizon?
It's the convention set by the IPCC and adopted by the GHG Protocol. Some reports also use a 20-year horizon, which gives short-lived gases like methane a much higher weighting (GWP ~82 instead of 28).
What's the difference between CO2e and CO2eq?
None — they're the same thing. CO2e, CO2eq and CO2-equivalent are used interchangeably.
How does URLCarbon report CO2e?
Every URLCarbon report gives a cradle-to-grave CO2e total in kilograms, broken down by lifecycle stage and material, following ISO 14067 principles.
Get a CO2e footprint for your product
Paste any product URL and URLCarbon generates a full cradle-to-grave CO2e report in seconds — aligned with ISO 14067 and the GHG Protocol.