Compare the price per kilometer between ethanol and gasoline using the 70% rule or custom vehicle mileage, projecting full-tank range and monthly fuel savings.
The real break-even point depends on your vehicle's actual consumption difference. For a more accurate comparison, use "My car" mode with your own measured km/L (or mi/gal).
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Price ratio and the 70% threshold.
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An ethanol vs. gasoline calculator that compares the two fuels' prices using the 70% rule or your car's actual mileage (km/L), calculating the break-even point, cost per 100 km, full-tank driving range, and estimated monthly savings.
In quick mode, the tool only compares the price ratio against the 70% threshold. In 'My car' mode, it uses your vehicle's actual mileage to work out cost per 100 km, full-tank range, and monthly savings.
Ethanol has lower energy density than gasoline, so a flex-fuel car generally drives fewer kilometers on a liter of ethanol than on a liter of gasoline. Historically, that ratio sits around 70% — if ethanol costs less than 70% of gasoline's price, it tends to pay off financially even though it delivers less energy per liter.
ratio = ethanolPrice / gasolinePriceIn 'Quick decision' mode, the tool only uses the two prices you enter and the fixed 70% threshold — no range, cost per km, or monthly savings is calculated or shown, because no actual consumption was provided.
Modern flex-fuel cars rarely land exactly on 70% — the real ratio typically falls between 65% and 75% depending on the engine, model year, and city/highway driving mix. Entering the km/L you measured with each fuel makes the break-even point specific to your car instead of the generic reference.
threshold = ethanolKm/L / gasolineKm/LYour car's real break-even point is 70.8% — close to the generic 70% rule, but not identical.
8.5 / 12 = 0.708 = 70.8%Comparing only the price per liter or the cost to fill the tank can be misleading, because the two fuels deliver different mileage. The cost to drive the same distance (100 km) with each fuel is the most direct comparison of what each option actually costs you.
The fuel with the lower cost per km can still require more frequent refueling, because it delivers fewer kilometers per full tank. The tool shows each fuel's theoretical range side by side so that trade-off stays visible alongside cost.
Prices, mileage, and every calculation stay in your browser — nothing is sent to a server. Results depend entirely on the prices and mileage you enter; always check the current values at the pump before deciding.
Because those estimates require your car's actual km/L, which is only entered in 'My car' mode. Quick mode compares only the price ratio, so it never invents consumption numbers you haven't provided.
Probably not exactly — the real ratio ranges from about 65% to 75% for most modern flex-fuel cars, depending on the engine and driving style. Use 'My car' mode with your measured km/L for a break-even point specific to your vehicle instead of the generic reference.
Fill the tank, reset the trip odometer (or note the mileage), drive normally until the tank runs low, then divide the distance covered by the liters needed to refill. Do this separately with ethanol and gasoline to get the two values the tool asks for.
Because equal-sized tanks don't hold the same amount of usable energy — ethanol delivers fewer km per liter. Fill-up cost ignores that gap; cost per 100 km compares both fuels by the actual distance each one delivers.
Yes, but only in 'My car' mode — it multiplies the cost-per-km difference by the monthly mileage you enter in the optional planning field.
It happens when the price ratio lands very close to the break-even threshold (within 0.5 percentage points) — in that case, the cost difference between the two fuels is too small for a practical conclusion.
No — flex-fuel vehicles have an oxygen sensor and an electronic control unit that detect the blend ratio in the tank and adjust the fuel injection automatically, so switching between or mixing the two fuels is safe for the engine.
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