How we calculate CO₂ savings

When you mark a ride as a Commute and tell us what transport you replaced, Riding Places credits the CO₂ you avoided by riding instead. The calculation is deliberately simple and auditable:

CO₂ avoided (kg) = distance (km) × emission factor (kg CO₂ per km)

The emission factors come from government datasets, and each commute is worked out the distance-based way the GHG Protocol sets out for employee commuting (Scope 3, Category 7). The result is CO2 avoided, which the GHG Protocol says to report separately from your Scope 1, 2 and 3 totals. We publish the factors here in full, drawn from the same source of truth the app calculates with, so this page can never silently disagree with your rides.

Emission factors

Factors for United States (kg CO₂ per km). Each row lists the exact published figure it derives from.

Which factor applies to your ride?

When you choose the transport yourself, we use the factor for that mode in your home market. Riding Places is not location-aware for this on purpose: "what would you otherwise have driven?" almost always means your vehicle, which is at home - and asking your phone for its location fails exactly when you are traveling.

When a ride is classified as a commute automatically (because it passed through a workplace GeoZone your group set up), we never got to ask which vehicle you would have driven. So we use a car of unknown size. The UK government publishes a figure for exactly that situation; for the US, where EPA does not, we blend EPA's car and light-truck figures by how far each is driven. It is an honest "we don't know your car", not an assumption dressed up as precision. These rides use the market of the group that owns the workplace zone, since that zone is a fixed place. You can always open the ride and set the real mode yourself; once you do, we keep your choice.

Why don't your past rides change?

Each ride is stamped with the exact methodology version used at the time (us-v1 today), and we never go back and recalculate old rides. If we adopt a newer dataset, only rides recorded afterwards use it. Most tools quietly restate history when their numbers change; we don't. The honest trade-off: after a version change, a long-running group total can blend two methodologies - which we would rather disclose than hide behind a silently-restated number.

Caveats worth knowing

• The measurement boundary is not uniform across modes. Electric transit rail includes the emissions from generating its electricity, while cars and buses count only fuel burned in the vehicle (not the emissions of refining that fuel). The net effect keeps cycling savings conservative.
• EPA publishes one nationwide bus figure, averaged across every kind of bus at about 20 passengers each (Federal Highway Administration, 2022). It does not publish a figure for city transit buses alone.
• EPA’s edition label runs ahead of the underlying data: the January 2025 Hub carries 2022 road data and older rail data. We pin the exact edition rather than tracking "latest".

Wherever we had to choose between a higher and a lower figure, we took the more conservative one - so if anything, these numbers understate rather than overstate what you saved.

Source: EPA GHG Emission Factors Hub, January 2025, Table 10. Methodology version us-v1, source last reviewed 16 July 2026. We pin the exact edition of each dataset rather than tracking "latest", and re-verify it before adopting a new one.