Free Online Engineering Tools
🍃 EV vs Fuel Emissions

CO₂ Emission Calculator

See how much carbon dioxide you save each year by driving electric instead of petrol or diesel — based on your mileage, your car's efficiency and how clean your electricity is.

🚗 Your Driving
Distance per year
km
1k50k
Fuel economy
L/100km
thirstyefficient
EV efficiency
kWh/100km
efficientheavy
Grid carbon intensity
g/kWh
cleancoal
1,692
kg CO₂ saved / year
050%100%
🌍 CO₂ Reduction
0255075100
61%
Strong saving
less CO₂ than petrol/diesel
EV 🌿1.08 t CO₂/yrPetrol / Diesel2.77 t CO₂/yr
In-use (well-to-wheel) CO₂ per year — the EV's figure depends on how clean your grid is.
Petrol/diesel CO₂
2,772 kg
EV CO₂
1,080 kg
CO₂ saved / year
1,692 kg
Tree-years to absorb
81 trees

Figures are in-use (well-to-wheel) estimates and exclude vehicle and battery manufacturing. Petrol is taken as 2.31 kg CO₂/L and diesel 2.68 kg CO₂/L; EV CO₂ = electricity used × your grid's carbon intensity.

How the CO₂ Is Calculated

Petrol/Diesel: CO₂ = distance ÷ 100 × litres per 100 km × emission factor (2.31 petrol, 2.68 diesel kg/L).

Electric: CO₂ = distance ÷ 100 × kWh per 100 km × grid intensity (g/kWh) ÷ 1000.

Saved: petrol/diesel CO₂ − EV CO₂.

How Much CO₂ Does a Car Emit?

Road transport is one of the largest sources of personal carbon emissions, and switching from a petrol or diesel car to an electric vehicle (EV) is one of the biggest single ways to cut yours. Exactly how much CO₂ you produce — and how much you save by going electric — depends on three things: how far you drive, how efficient each vehicle is, and how clean the electricity that charges the EV is. This calculator compares the yearly in-use (well-to-wheel) carbon dioxide of a fuel car against an EV on your grid and shows the difference.

A typical petrol car driven 15,000 km a year emits around 2.5–3 tonnes of CO₂. On an average grid an EV covering the same distance usually cuts that by 50–70%, and on a clean hydro or renewable grid the reduction can exceed 90%.

Tip: EVs save money as well as carbon — see our EV vs Gas Savings Calculator for the running-cost side.

Note: These are estimates for in-use emissions and exclude the CO₂ from manufacturing each vehicle and its battery. They are intended for general awareness, not formal carbon accounting.

How Car CO₂ Is Calculated

For a combustion car, CO₂ comes directly from the fuel burned; for an EV, it comes from the electricity used and how that electricity is generated.

Petrol / Diesel: CO₂ = distance ÷ 100 × litres per 100 km × emission factor.

Electric: CO₂ = distance ÷ 100 × kWh per 100 km × grid intensity (g/kWh) ÷ 1000.
SourceEmission factorRoughly per km*
Petrol / gasoline~2.31 kg CO₂ / litre~185 g/km at 8 L/100km
Diesel~2.68 kg CO₂ / litre~161 g/km at 6 L/100km
ElectricityGrid intensity (g CO₂ / kWh)0–150+ g/km by grid

*Per-km figures are examples for the economies shown; your result above uses the exact numbers you enter.

Why the Electricity Grid Decides EV Emissions

An EV produces no tailpipe emissions, but it is only as clean as the electricity used to charge it. That is captured by the grid carbon intensity — the grams of CO₂ per kilowatt-hour. The greener your power, the closer your EV gets to zero in-use emissions. Typical values vary enormously around the world:

Grid type (example)Approx. intensity
Hydro / renewable-heavy~30–60 g CO₂/kWh
Low-carbon mix~150–250 g/kWh
World average~450–500 g/kWh
Fossil-heavy~600–700 g/kWh
Coal-dominated~800–850 g/kWh

Petrol vs Diesel vs EV: Typical Annual CO₂

Here is how a year of driving 15,000 km compares for different vehicles (in-use CO₂):

VehicleAssumptionAnnual CO₂
Petrol car8 L/100km~2.77 t
Diesel car6.5 L/100km~2.61 t
EV – coal grid18 kWh/100km, 820 g/kWh~2.21 t
EV – average grid18 kWh/100km, 400 g/kWh~1.08 t
EV – clean grid18 kWh/100km, 50 g/kWh~0.14 t

Well-to-Wheel vs Tailpipe

"Tailpipe" emissions are only what comes out of the exhaust. "Well-to-wheel" also counts the energy used to produce and deliver the fuel or electricity, which is the fairer way to compare an EV with a combustion car. This tool uses an in-use well-to-wheel approach: fuel burned for the combustion car, and grid electricity for the EV.

What About Building the Car?

Manufacturing any vehicle creates CO₂, and an EV battery makes its production footprint larger than a comparable petrol car. However, because the EV emits so much less while driving, it typically "pays back" that extra manufacturing carbon within a few years, then stays well ahead over the car lifetime — especially on a clean grid. Lifetime studies consistently find EVs lower-carbon than equivalent petrol cars in almost every market.

Putting a Tonne of CO₂ in Perspective

One tonne of CO₂ is hard to picture, so the calculator translates your yearly saving into tree-years — a mature tree absorbs about 21 kg of CO₂ per year, so a tonne takes roughly 48 tree-years to absorb. For comparison, a single long-haul return flight can emit one to two tonnes of CO₂ per passenger, which shows how quickly driving emissions add up over a year.

Tips to Cut Your Driving Emissions Further

Frequently Asked Questions

How much CO₂ does a car emit per year?

A typical petrol car driven 15,000 km a year emits roughly 2.5–3 tonnes of CO₂. Each litre of petrol releases about 2.31 kg and each litre of diesel about 2.68 kg.

How much CO₂ does an electric car save?

It depends on mileage and how clean your electricity is. An EV on an average grid often cuts driving CO₂ by 50–70% versus petrol, and by more than 90% on a clean grid.

How many grams of CO₂ per km does a car emit?

A petrol car at 8 L/100km emits about 185 g/km; a diesel at 6 L/100km about 161 g/km. An EV ranges from near zero on renewables to over 150 g/km on coal.

Do electric cars really produce zero emissions?

They have no tailpipe emissions, but charging uses grid electricity that may come from fossil fuels, so their real CO₂ depends on the grid intensity.

Are EVs cleaner even on a coal-heavy grid?

Usually, but by a smaller margin. Electric motors are far more efficient than engines, so even on a dirty grid an EV often matches or beats an efficient petrol car.

Why does the grid matter for EV emissions?

An EV is only as clean as the power that charges it — under 100 g CO₂/kWh on a renewable grid, over 800 g on a coal-heavy one.

Does this include manufacturing emissions?

No. It compares in-use driving emissions. Manufacturing, especially the battery, adds CO₂ that EVs typically offset within a few years of driving.

How many trees offset a tonne of CO₂?

A mature tree absorbs about 21 kg of CO₂ per year, so a tonne takes roughly 48 tree-years. The calculator shows the tree equivalent of your yearly saving.

Sources & References

Fuel emission factors follow standard values used by the U.S. EPA Green Vehicle Guide; grid carbon intensity and EV lifecycle context draw on the International Energy Agency (IEA). Figures are general estimates, not formal carbon accounting.