About Carbonnest

Carbonnest is a collection of free carbon and energy calculators. Each tool answers one clear question — how much CO₂ does this kWh, mile, flight, or gallon of fuel produce — without requiring an account or personal data.

Every calculator explains the factors or assumptions used in its result and links to published sources where applicable, so you can check the maths yourself.

The Carbonnest editorial and engineering team selects the sources, maintains the calculator formulas, reviews corrections, and publishes updates to this site. Editorial, operational, and privacy enquiries can be sent to bkapamulomo@bluecodeltd.com.

Emission factors are drawn from published government and research datasets, including UK Government greenhouse-gas conversion factors, the US Environmental Protection Agency, and Ember’s global electricity data as processed by Our World in Data.

Every factor records its source year and calculation boundary. We review time-sensitive factors when a new annual dataset is published and retain a clear distinction between combustion, use-phase and lifecycle estimates.

Formula logic is separated from the interface and checked with repeatable unit tests. Unit conversions use published definitions: one mile is 1.609344 kilometres, one US gallon is 3.785411784 litres, and one imperial gallon is 4.54609 litres.

We test zero and invalid inputs, equivalent metric and imperial vehicle scenarios, and multi-year solar cash flows. Material assumptions and exclusions are stated on each calculator page so a result can be reproduced and challenged.

Carbonnest is free to use and supported by advertising. Ads never change the numbers a calculator produces, and we never sell your personal information.

Questions, corrections to a factor, or a calculator you'd like to see? Email us at bkapamulomo@bluecodeltd.com.