Fuel Cost Calculator

Calculate Fuel Cost

km
L/100km
$

Fuel Needed

30.0 L

Trip Cost

$48.00

See how this is calculated

How This Calculation Works

This calculator estimates how much fuel a trip will use and what it will cost, based on your vehicle's fuel efficiency. In metric units, it divides your trip distance by 100, multiplies by your car's consumption rate (liters per 100 km), to find total liters needed. In imperial units, it simply divides trip distance by your car's miles-per-gallon rating.

The fuel needed is then multiplied by the current price per liter or gallon to get the total trip cost. This is a straightforward, direct calculation — the accuracy depends entirely on how accurate your fuel efficiency figure is, since real-world consumption can vary from a vehicle's rated or advertised figures.

Fuel efficiency isn't constant — it changes with driving style, speed, terrain, load, tire pressure, and weather. Using your vehicle's actual observed average (calculated from a few fill-ups) tends to be more accurate than relying on the manufacturer's official rating alone.

Common Mistakes to Avoid

  • Using the manufacturer's rated MPG instead of real-world MPG. Official fuel economy ratings are measured under standardized test conditions and often don't match real-world driving, especially in stop-and-go city traffic or hilly terrain. Use your own tracked average when possible.
  • Forgetting highway vs. city differences. Most vehicles get noticeably different fuel economy on the highway versus in the city. If your trip is mostly one or the other, use the corresponding rating rather than a blended average.
  • Ignoring load and cargo. A fully loaded vehicle, roof rack, or trailer can meaningfully reduce fuel economy — sometimes by 10-20% or more — compared to an unloaded vehicle.
  • Not accounting for fuel price changes on long trips. Fuel prices vary by region and can change during a long road trip. For multi-day trips, consider using a slightly higher price estimate as a buffer.

Worked Example

Scenario: A 400 km trip in a car that consumes 7.5 L/100km, with fuel priced at $1.60/liter.

Step 1 — Fuel needed: (400 ÷ 100) × 7.5 = 30 liters.

Step 2 — Total cost: 30 × $1.60 = $48.00 for the trip.

Frequently Asked Questions

How do I find my car's actual fuel consumption?
Fill your tank completely, reset your trip odometer, drive normally until you need to refuel, then fill up again and note how many liters or gallons it took. Divide the distance driven by the fuel used (or use the calculator's fields to convert) to get your real-world consumption rate.
Why is my actual fuel cost higher than this calculator estimates?
Real-world driving factors — traffic, aggressive acceleration, high speeds, cold weather, air conditioning use, and carrying extra weight — can all reduce fuel economy below rated or average figures. Using your own tracked average, rather than an official rating, usually produces more accurate estimates.
Does highway or city driving use more fuel?
It depends on the vehicle. Most gasoline cars are more efficient on the highway at moderate speeds due to steady engine operation, while city stop-and-go driving increases fuel use. Hybrid vehicles are often the opposite, since they're more efficient at low speeds where the electric motor does more of the work.
How can I reduce my fuel costs on a trip?
Maintaining steady speeds, keeping tires properly inflated, removing unnecessary weight and roof racks, using cruise control on highways, and avoiding aggressive acceleration and braking are all proven ways to meaningfully improve real-world fuel economy.

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