Commute Emissions Comparison Calculator

Frequently Asked Questions

• How does the commute calculator work?+
  You enter your one-way distance and the tool doubles it for a round trip, multiplies by the number of workdays you commute in a year, and then by a per-kilometre CO₂ factor for each mode of transport. It does the same with a rough per-kilometre cost, so you can compare every option by both carbon and money for a full year.
• Which mode is the lowest carbon?+
  Walking and cycling are effectively zero. Among motorised modes, rail and a full bus are usually lowest per passenger because the vehicle’s emissions are shared across many people, followed by e-scooters, then motorbikes, with a solo petrol car the highest. The ranked chart shows exactly where your distance places each option.
• Why is a car so much worse than the bus or train?+
  A car typically carries one person but burns fuel to move over a tonne of metal, so all of that carbon is attributed to a single commuter. Public transport spreads the vehicle’s emissions across dozens of passengers, dramatically lowering the figure per person. That sharing effect is the single biggest reason transit is cleaner.
• How are the costs estimated?+
  Costs are rough per-kilometre estimates: fuel-based for car and motorbike and fare-based for public transport, shown in your selected region’s currency. They are starting points for comparison rather than exact fares, so adjust your expectations to local prices — the carbon ranking is the more robust output.
• Does the calculator include the motorbike, which is common in ASEAN?+
  Yes. Motorbikes and scooters are a dominant mode across much of Southeast Asia, so they are included with their own factor. They sit well below a car but above public transport, which is useful for the many commuters weighing a bike against a car or the train.
• What is the “switch insight”?+
  It highlights the practical saving from a common change — moving a car commute to rail — in both kilograms of CO₂ and money per year. Seeing the concrete annual figure often makes the case for a switch far more compelling than an abstract per-trip number.
• How many workdays should I use?+
  A typical full-time commuter travels on roughly 220–240 days a year after weekends, public holidays and leave. The default is 240; lower it if you work from home some days, which itself is one of the biggest ways to cut commuting emissions.
• Are e-scooters really low carbon?+
  They use very little energy per kilometre, so their direct footprint is small, but because they run on electricity their true carbon depends on how clean the grid is. On a coal-heavy grid the figure is higher than on a grid with lots of renewables; the factor used here is a representative average.
• How accurate are these figures?+
  They are good averages for comparison, not a precise audit. Real emissions depend on your specific vehicle, traffic, how full the bus or train is, and the local electricity mix. Use the tool to compare modes and size the benefit of switching, not as an exact measurement of your particular journey.
• Where do the CO₂ factors come from?+
  They are planning estimates chosen to sit close to the UK Government (DESNZ with Defra) 2025 greenhouse-gas conversion factors, which are the most widely used public set: the car figure of 0.170 kg per km compares with the published 0.163 for an average petrol car and 0.167 for a car of unknown fuel; the motorbike 0.103 with 0.101 for a medium motorbike; the bus 0.097 with 0.104 for an average local bus; and the rail 0.035 with 0.035 for national rail. Those published figures describe UK vehicles and UK occupancy, not a Singapore MRT carriage or a Jakarta bus, so treat the ranking as robust and the exact kilograms as indicative. The e-scooter figure and the per-kilometre costs have no published source and are the weakest numbers on the page. Open the “How is this calculated?” panel to see every factor in use.