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Driving Carbon Footprint Calculator
Estimates tailpipe CO₂ (and CO₂-equivalent including methane and nitrous oxide) for a car trip from distance and fuel economy or fuel used, using per-litre combustion factors for petrol, diesel and LPG, and scales to a yearly total.
When to use
You want the CO₂ emissions of a commute, road trip or annual mileage for a petrol, diesel or LPG vehicle, in kilograms and grams per kilometre.
Do not use when: The vehicle is electric or plug-in hybrid (use carbon-footprint-electricity with the kWh consumed), you need lifecycle/well-to-wheel emissions, or you only need the fuel cost (use fuel-cost).
Formula
fuel_L = distance_km × L/100km ÷ 100 (mpg converted via 235.215/mpg_US or 282.481/mpg_UK; km/L via 100/(km/L)); CO₂ = fuel_L × factor (petrol 2.31, diesel 2.68, LPG 1.51 kg/L); CO₂e = CO₂ / 0.994; per year = per trip × trips_per_year
Tank-to-wheel combustion factors as of 2024: they match the UK DEFRA/DESNZ 2024 factors for 100 % mineral petrol and diesel and the US EPA values (8,887 g CO₂ per US gallon of petrol = 2.35 kg/L, 10,180 g/gal diesel = 2.69 kg/L) within 2 %. Upstream (well-to-tank) emissions add roughly 20 % and are not included.
Inputs
| Parameter | Type | Unit | Required | Description |
|---|---|---|---|---|
distance | number | yes | Distance of one trip in distance_unit. Range: > 0, ≤ 1000000 | |
distance_unit | enum: km | mi | default km | Unit of the distance. | |
fuel_economy | number | no | Vehicle fuel economy in fuel_economy_unit. Not needed when fuel_used_liters is given. Range: > 0, ≤ 1000 | |
fuel_economy_unit | enum: l_per_100km | mpg_us | mpg_uk | km_per_l | default l_per_100km | Unit of fuel_economy. | |
fuel_used_liters | number | L | no | Litres of fuel burned on the trip, if known; overrides fuel_economy. Range: > 0, ≤ 100000 |
fuel_type | enum: petrol | diesel | lpg | default petrol | Fuel burned; selects the kg CO₂ per litre combustion factor. | |
trips_per_year | number | default 1 | How many times the trip is driven per year (e.g. 230 for a one-way daily commute, 460 for both directions). Range: ≥ 1, ≤ 100000 |
Outputs
| Output | Type | Unit | Description |
|---|---|---|---|
fuel_liters | number | L | Litres of fuel burned on one trip. |
co2_kg_per_trip | number | kg | Tailpipe carbon dioxide from combustion, fuel_liters × factor. |
co2e_kg_per_trip | number | kg | Tailpipe greenhouse gases including CH₄ and N₂O, CO₂ ÷ 0.994 (EPA 2022 ratio for passenger vehicles). |
co2_g_per_km | number | g/km | Grams of CO₂ per kilometre driven. |
co2_kg_per_year | number | kg | co2_kg_per_trip × trips_per_year. |
co2e_kg_per_year | number | kg | co2e_kg_per_trip × trips_per_year. |
emission_factor_kg_per_liter | number | kg CO₂/L | Combustion factor applied for the selected fuel. |
distance_km | number | km | Trip distance in kilometres. |
Example
100 km at 7 L/100 km, petrol, 230 trips/year: {"distance":100,"distance_unit":"km","fuel_economy":7,"fuel_economy_unit":"l_per_100km","fuel_type":"petrol","trips_per_year":230} → {"fuel_liters":7,"co2_kg_per_trip":16.17,"co2e_kg_per_trip":16.27,"co2_g_per_km":161.7,"co2_kg_per_year":3719.1,"emission_factor_kg_per_liter":2.31}
30 miles at 30 mpg (US), diesel: {"distance":30,"distance_unit":"mi","fuel_economy":30,"fuel_economy_unit":"mpg_us","fuel_type":"diesel"} → {"distance_km":48.28,"fuel_liters":3.79,"co2_kg_per_trip":10.14,"co2_g_per_km":210.1}
GET https://tttkmbb.com/api/v1/calculate/carbon-footprint-driving?distance=100&distance_unit=km&fuel_economy=7&fuel_economy_unit=l_per_100km&fuel_type=petrol&trips_per_year=230
Machine access
- API:
GET https://tttkmbb.com/api/v1/calculate/carbon-footprint-driving(query parameters) orPOSTwith a JSON body{"inputs": {...}} - Schema: https://tttkmbb.com/api/v1/calculators/carbon-footprint-driving · Markdown: https://tttkmbb.com/weather/carbon-footprint-driving.md · JSON definition: https://tttkmbb.com/weather/carbon-footprint-driving.json
- MCP: server
https://tttkmbb.com/mcp, toolrun_calculator with calculator_id="carbon-footprint-driving" - OpenAPI operationId:
estimate_driving_carbon_footprint - Freshness:
static. Authentication: none. Rate limit: fair use (see rate limits).
Sources
- US EPA – Greenhouse Gas Emissions from a Typical Passenger Vehicle (8,887 g CO₂/gal petrol, 10,180 g CO₂/gal diesel) (government)
- UK DESNZ/DEFRA – Greenhouse gas reporting: conversion factors 2024 (fuels per litre, electricity) (government)
- US EPA – Greenhouse Gas Equivalencies Calculator: calculations and references (eGRID 2022 US average 823.1 lb CO₂/MWh; vehicle CO₂/GHG ratio 0.994) (government)
FAQ
Why is diesel's factor higher if diesel cars emit less?
Diesel contains more carbon per litre (2.68 vs 2.31 kg CO₂), but diesel engines use fewer litres per 100 km; compare grams per kilometre, not per litre.
What is the difference between CO₂ and CO₂e here?
CO₂e adds the tailpipe methane and nitrous oxide weighted by global-warming potential; for modern cars that is under 1 % (EPA ratio 0.994), so both numbers are close.
Does this include fuel production?
No. Well-to-tank emissions from extracting, refining and transporting the fuel add about 20 % (DEFRA well-to-tank factors); electricity and lifecycle comparisons should include them.
Related calculators
- Electricity Carbon Footprint Calculator — Emissions of electricity use, including EV charging.
- Fuel Cost Calculator — Cost of the same trip from fuel price and economy.
- Fuel Economy Converter — Convert between L/100 km, mpg and km/L.