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Ethanol or petrol? Fuel calculator for flex cars (Brazil)

Type the two prices at the pump and find out which fuel costs less per kilometre, the highest ethanol price that still pays off and how much you save a month.

Free, no sign-up to use · what you type or add stays on your device · works offline · How it works

R$ /L
R$ /L
km
Your car’s consumption
km/L
km/L

Look it up on the car’s Inmetro label or in the manual, or measure it: fill the tank, reset the trip meter and divide the km by the litres at the next fill-up.

Pump price comparison

Fill up with

Ethanol

Ethanol costs 66.6% of the petrol price; with this car it pays off up to 70%.

Ethanol pays off up to
R$ 4.40
Savings per month
R$ 27.66
Savings per year
R$ 331.92
FuelPer kmPer month
Ethanol
R$ 4.19/L · 7.7 km/L		R$ 0.544R$ 544.16
Petrol
R$ 6.29/L · 11 km/L		R$ 0.572R$ 571.82

At R$ 6.29 for petrol, ethanol is worth it up to R$ 4.40 a litre. Driving 1,000 km a month, that saves R$ 27.66 a month (R$ 331.92 a year).

The starting prices are only an example: type the ones at your petrol station. The 70% rule is an average; with your car’s real consumption the answer is exact.

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About this tool

In Brazil most cars are flex: they run on ethanol, petrol or any mix of the two. Ethanol is cheaper per litre but goes fewer kilometres, so the question at the pump is which one costs less per km. Type the price of each fuel and how far you drive a month. The calculator starts with the usual 70% ratio (7.7 km/L on ethanol and 11 km/L on petrol); open "Your car’s consumption" to use your own figures and get the exact break-even for your car. It shows which fuel to choose, the cost per km and per month of each, the highest ethanol price that still pays off and the savings per month and per year. Everything is calculated in your browser.

How to use it

  1. 1 Type the price per litre of ethanol and of petrol at your petrol station.
  2. 2 Type roughly how many kilometres you drive a month.
  3. 3 Optionally, open “Your car’s consumption” and type the km per litre with each fuel (Inmetro label, manual or your own measurement).
  4. 4 Read which fuel to choose, the highest ethanol price that pays off and how much you save.

Frequently asked questions

Why the 70% rule?

A litre of ethanol holds about 30% less energy than a litre of petrol, so a flex car goes roughly 30% fewer kilometres with it. Ethanol pays off while it costs less than about 70% of the petrol price. The real ratio changes from car to car, usually between 65% and 75%; with your car’s consumption the calculator uses the exact one.

Where do I find my car’s consumption?

On the Inmetro consumption label (PBE Veicular), which lists the km per litre in town and on the road with each fuel, or in the manual. The most accurate figure is your own: fill the tank, reset the trip meter and, at the next fill-up, divide the kilometres driven by the litres you put in.

Can I mix ethanol and petrol in the tank?

Yes. Flex engines are made to run on any mix, and the electronics adjust on their own. A mix costs per km somewhere between the two fuels.

Does it depend on where I live?

Yes, because prices change a lot by state: in states that produce ethanol it often pays off, in others it rarely does. Always compare the prices at the station where you will fill up.

Is my data sent anywhere?

No. The calculation runs in your browser and nothing you type is sent or stored.

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