How the CO₂ estimate works
Last updated: 12 October 2026 · Version 2026-10-12
An estimate of the change in driving emissions compared with your original stop order.
The comparison
We compare the road distance for the addresses in the order you entered them with the road distance for OptiRoute’s planned order. Both use the same start, finish, vehicle factor and road-routing distance data. Road distances are for the routing engine’s fastest paths between stops, rather than straight lines. This is not a comparison against other route-planning products.
The optimiser aims to reduce driving time. A faster route can cover more miles; when this happens, we show an estimated emissions increase. We do not turn an increase into a saving. If comparable road distances are unavailable, we display “Estimate unavailable” and still provide the route.
The calculation
Estimated driving emissions (kg CO₂e) = road distance (km) × the selected average vehicle factor.
Estimated reduction = original-order emissions − planned-order emissions. A negative result means an increase.
CO₂e means carbon dioxide equivalent and includes the greenhouse gases represented by the vehicle factor. We round the displayed estimate to one decimal place, so a very small difference may show as no material change. The downloadable estimate includes more decimal places for transparency, rather than implying measured accuracy.
Factors used
Source: UK government greenhouse gas conversion factors 2026, published by the Department for Energy Security and Net Zero. We use the 2026 flat file, version 1.2, revised July 2026, and the Scope 1 total CO₂e factor per vehicle-kilometre.
| Selection | kg CO₂e / km | Source factor ID |
|---|---|---|
| Average petrol car | 0.16152 | 4_301_3070_4_1 |
| Average diesel car | 0.17265 | 4_301_3069_4_1 |
| Average diesel van, up to 3.5 tonnes | 0.25716 | 5_303_3102_4_1 |
The vehicle choice changes the estimate, not the routing profile. Electric and other vehicles do not receive an estimate in this version. We review factors when a new annual set is available. Contains public sector information licensed under the Open Government Licence v3.0.
What it includes and excludes
These are average driving emissions for the selected petrol or diesel vehicle category. The estimate excludes fuel extraction/refining/distribution, vehicle manufacture, maintenance, website/server emissions and other lifecycle impacts. It is not a measure of the overall environmental benefit of OptiRoute.
Actual emissions vary with the specific vehicle, load, driving style, weather, congestion and idling. The driving-time model has no live traffic. Your navigation app may choose different roads, and a postcode or manually adjusted entrance pin can change distances. This estimate is not a verified carbon account, certified saving, offset or carbon credit.
Keeping a copy
Open “How this is estimated” in the route result and choose “Download estimate” for a CSV showing both distances, both emissions estimates, the signed difference, factor, source and calculation boundary. The route can also be printed. We do not add route savings to a public total or claim a saving for a trip that you have not driven.