Offsetting your driving

How to drive and be climate positive: an easy way to offset your CO2 emissions from driving.

I was asked how many trees would we need to plant to offset carbon emissions from driving 10,000km. But because different vehicles consume fuel differently – think Mack Truck vs Smart Fortwo – it seems better to focus on fuel.


Smart Fortwo cars consume less fuel per 10,000km than Mack Trucks.
Smart Fortwo cars consume less fuel per 10,000km than Mack Trucks.

We want to offset our fuel consumption and make it easy to do it. So let’s do some research.


One minute of research: CO2 emissions from burning one litre of unleaded petrol



One minute of research into Carbon in petrol.
One minute of research into Carbon in petrol.

One minute of research in CO2 emissions in fuel.
One minute of research in CO2 emissions in fuel.

Burning 1 litre of unleaded petrol contains 652 grams of carbon. Carbon needs a bunch of oxygen to turn it into CO2, and a burning a litre of unleaded petrol creates 2.31kg of CO2. A litre of diesel emits 2.68kg of CO2 (16% more than petrol) and a litre of LPG contains about 454g of carbon which converts into 1.51kg of CO2 when adding oxygen during burning (a third less than petrol). But let’s work with petrol first.

So 1 tonne of CO2 is emitted from using 433 litres of fuel. So based on my earlier blog calc where we’d plant 18 trees to offset a tonne of CO2 and then triple offset it to be Climate Positive rather than just neutral so we’d be planting 54 trees instead of 18 to triple offset a tonne of CO2 emissions, then that’s 54 trees for 433 litres bought at the pump.

Whatever your car or fuel consumption, that’s 0.125 trees per litre. Which is difficult to plant. But planting 1 tree per 8 litres might be easier. And that’s already triple offset. So let’s work with that.

(Triple Offset means you pay for you and two other people, so you’re not driving neutral, you’re driving positive; climate positive. You’re essentially saving the world more while driving about.)

So my suggestion would be to plant the tree at the time you fill up your car with fuel. Use the Impact Now app by B1G1 and when putting fuel in the car, plant one tree for every 8 litres purchased or part thereof.

You might want to not use your phone right next to the fuel pump, as giant explosions in fuel stations tend to release lots of carbon into the atmosphere. Instead do it at the cash register inside.


Explosions are bad.
Explosions are bad.

So, explosion averted, how many trees do you plant? You’d plant 4 trees if you put in 32 litres or less, and 8 trees if between 33 and 64 litres, 12 trees for 65-96 litres, 16 trees per tank for 97 litres and above. If you’re driving a Mack truck, the tank is 265 litres, so you’d plant 34 trees for a full tank.

Or, if you know the size of your tank, you could avoid calculating anything because I’m about to do all that for you.


What’s the size of my fuel tank in my car / ute / van / truck / motorbike?

Most average cars have a tank that’s about 45-65 litres. So you’d pretty much plant 6-8 trees every time you fill up. 6 trees for a small car, 8 trees for an average-sized car.

A micro-sized car like the Smart Fortwo has a 33-litre tank so you could get away with a smart four-tree fill… unless you pushed your car to the fuel pump in which case you’re up for 5 trees.

SUV tanks are 70-105 litres: small SUV 9 trees, big SUV 13 trees.

Utes 70-80 litres: 9-10 trees.