Fuel & Trip Cost Calculator

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fuel cost per 100 km

Fuel cost per 100 km

A quick way to compare cars or budget a trip: what it costs to drive exactly 100 km at the consumption and fuel price you enter.

Why 100 km is a useful reference

A hundred kilometers is a round, easy-to-compare unit: dividing 100 by the consumption in km/l gives the liters that stretch burns, and multiplying by the fuel price gives the cost. It is the same math used to estimate any trip's cost, just with the distance fixed at 100 km to make comparisons easier.
To compare two cars fairly, use each one's real consumption (not the factory figure) at the same fuel price, the car with the lower cost per 100 km is the cheaper one to drive day to day.

100 km examples

Compact flex-fuel car

Input: 100 km, 12 km/l, preço 6,09
Expected output: ~8,3 litros, ~50,8 de custo

Reference figure, adjust to your car's real consumption.

Larger SUV

Input: 100 km, 8 km/l, preço 6,09
Expected output: ~12,5 litros, ~76,1 de custo

Lower mileage per liter raises the cost per 100 km.

Efficient hybrid

Input: 100 km, 18 km/l, preço 6,09
Expected output: ~5,6 litros, ~33,8 de custo

Roughly half the liters of the compact flex car for the same stretch.

Full tool FAQ

What is the ethanol 70% rule?

It is a popular Brazilian rule of thumb that compares only the pump price of the two fuels: divide the ethanol price by the gasoline price, and if the result is below 0.70 (70%), ethanol tends to be the cheaper choice. The rule exists because ethanol holds roughly 30% less energy per liter than gasoline, so a flex-fuel car covers fewer kilometers on a liter of ethanol than on a liter of gasoline.

Is the precise calculation always better than the 70% rule?

How does splitting the cost among passengers change the result?

Does checking round trip automatically double the distance?

Can I use miles and gallons instead of kilometers and liters?

Does this calculator account for tolls, wear on the car, or other costs?

Is the data I type saved or sent to a server?

Why is my real fuel consumption usually different from what the manufacturer advertises?

Frequently asked questions

Can I use this to compare different cars?

Yes, that is one of the most common uses. Run the calculation with each car's consumption (keeping the same fuel price) and compare the cost per 100 km, the lower figure is the cheaper car to drive.

Can I change the distance from 100 km to something else?

Yes, the distance field is a normal input, 100 km is just this page's starting point. Type any distance to calculate a different stretch's cost.

Should I use the factory consumption figure or my car's real one?

Use the real one whenever you know it, it usually comes in lower than the factory figure because of traffic, air conditioning and driving style. A simple way to estimate it is dividing the km driven by the liters used between two full tanks.

Next steps