Skip to Content
  1. FAQ
  2. CO2e units — what is a metric ton of CO2e?

CO2e units — what is a metric ton of CO2e?

What is the 'e' in CO2e?

Carbon dioxide emissions make up only about 75% of total greenhouse gas emissions. Beyond carbon dioxide (CO2), the other quarter or so of emissions are made up of methane, nitrous oxide, hydrofluorocarbons, etc. Scientists have converted the global warming potential of all gases into carbon dioxide equivalents (CO2e), so that we have a single apples-to-apples unit to work with.

A note about units

CO2e is always measured in metric units. A metric ton (or tonne) is the equivalent of 1,000 kg — not to be confused with a 'ton' in the imperial system of measurement.


In Metric Tons

In Kilograms

Kilogram (kg)

0.001 t

1 kg

Metric Ton (t)

1 t

1,000 kg

Kilotonne (kt)

1,000 t

1 million kg

Megatonne (Mt)

1 million t

1 billion kg

Gigatonne (Gt)

1 billion t

1 trillion kg

To give you a sense of scale, here are some common items and their corresponding approximate emissions footprint in CO2e —


Producing a typical cheeseburger

5 kg CO2e


Burning a full tank of gas in your car (~14 gallon tank)

125 kg CO2e


Taking a roundtrip flight from NY to LA

1 t CO2e


The average total footprint per year of an American

18 t CO2e


Microsoft in 2020 (scope 1-3)

11 Mt CO2e


World emissions 2020

50 Gt CO2e