Commute Emissions Calculator
The greenhouse gas your commute produces in a year — by car, motorbike, bus, train, tram, e-bike, bicycle or on foot — and what switching modes would save.
Multiply the distance by the emissions per passenger-kilometre for the mode.
How the commute emissions calculator works
Multiply the distance by the emissions per passenger-kilometre for the mode. Typical figures: a petrol car about 170 g CO₂e/km with one occupant, diesel 160, hybrid 100, an electric car 50 on an average grid, a motorbike 110, a bus 100, a train 40, a tram 30, an e-bike 5, walking and cycling effectively zero. Factors vary with vehicle, occupancy and grid, so enter your own where you know it.
Formula: kg CO₂e per year = distance × 2 × days per week × weeks × factor (g/km) ÷ 1,000
Worked examples
| Inputs | CO₂e per year | Note |
|---|---|---|
| 15 km each way, petrol car, 5 days | 1,173 kg | 1,173 kg |
| Same trip by train | 276 kg | 276 kg |
| 5 km by e-bike, 4 days | 9 kg | 9 kg |
FAQFrequently asked questions
Where do the factors come from?
They are typical per-passenger-kilometre figures from national conversion-factor tables for a single-occupant car and average-loading public transport. Your own car’s figure is its fuel consumption times 2.3 kg per litre of petrol (2.7 diesel) divided by occupancy.
Why is the electric car not zero?
Its tailpipe is, but the electricity is not: 50 g/km assumes a grid around 300 g/kWh at 0.17 kWh/km. On a coal-heavy grid it is nearer 100–150; on a very clean one, under 20. Use the custom factor for your grid.
Does carpooling count?
Yes — divide the car factor by the number of people sharing. Two in a petrol car is 85 g/km each, already below the bus.
What about working from home?
Reduce the commuting days per week; two days at home cut the total by 40%. Home energy use rises a little, but for most people the net saving is large.
Where these figures come from
- UK DESNZ / DEFRA — Greenhouse gas reporting: conversion factors — the flight, fuel and waste emission factors used here
- Scarborough et al. (2014), Climatic Change — Dietary greenhouse gas emissions — the per-diet daily emission figures
- US EPA — Technical Assistance Document for the Reporting of Daily Air Quality (AQI) — the PM2.5 breakpoints the air quality calculator uses
- UK Department for Energy Security and Net Zero — conversion factors — the official UK emission factors
Last checked: September 2026. Factors are taken from published government and peer-reviewed sources, each named on the page with its year.