Fuel Cost Calculator
Calculate the fuel cost and consumption for any trip
Common trip costs (at current settings)
How to use:
- • Select MPG (US) or L/100km (metric) based on your vehicle
- • Enter your trip distance, vehicle fuel efficiency, and local fuel price
- • Results show fuel needed, total cost, and cost per mile/km
- • The comparison table shows costs for common trip distances
- • Use the current fuel price from your local gas station app
What this calculator estimates
This fuel cost calculator estimates how much you will spend on gasoline (or diesel) for any trip or regular commute. Enter your trip distance, your vehicle's fuel economy, and the current pump price, and the tool returns the total fuel cost along with a cost-per-mile (or cost-per-km) figure. It supports both the US customary system (miles and MPG) and the metric system (kilometres and litres per 100 km), so it is equally useful for drivers in North America, Europe, Australia, and anywhere else in the world.
Road-trip planners, daily commuters, fleet managers, and rideshare drivers all rely on this kind of estimate to budget accurately and compare vehicle running costs before buying or renting a car. You can also use it alongside our unit converter if you need to switch between miles and kilometres before entering your distance.
How fuel cost is calculated
The calculation has two straightforward steps regardless of which unit system you use: first find how much fuel the trip requires, then multiply by the price per unit of fuel.
US customary (MPG)
Fuel needed (gallons) = distance (miles) ÷ fuel economy (MPG)
Total cost = fuel needed × price per gallon
Because MPG expresses how far the car travels on one gallon, dividing distance by MPG gives you exactly how many gallons the engine will burn.
Metric (L/100 km)
Fuel needed (litres) = distance (km) × L/100 km ÷ 100
Total cost = fuel needed × price per litre
L/100 km expresses how many litres are consumed per 100 km, so you scale it by the actual distance divided by 100.
For a round trip, simply double the one-way distance before entering it, or multiply the one-way result by two. The comparison table below the calculator already shows you round-trip equivalent distances if you enter the one-way value.
Worked example: 300-mile road trip
Suppose you are driving 300 miles in a car rated at 30 MPG and your local gas station is charging $3.50 per gallon. Here is the calculation step by step:
Find fuel needed
300 miles ÷ 30 MPG = 10 gallons
Calculate one-way cost
10 gallons × $3.50 = $35.00 one way
Round-trip cost
$35.00 × 2 = $70.00 round trip
The cost per mile works out to $35 ÷ 300 = $0.117 per mile. If gas prices rise to $4.00/gallon the same trip costs $40 one way — a $5 increase for every $0.50 rise in pump price on a 300-mile journey. Try different values in the calculator above to see how sensitive your trip cost is to fuel prices.
MPG vs L/100 km — which direction is “better”?
The two standards measure fuel economy from opposite directions, which can be confusing when comparing vehicles from different countries.
MPG (distance per fuel)
Measures how far you travel on one unit of fuel. Higher is better — 40 MPG is more efficient than 25 MPG. Common in the US, UK (mpg Imperial), and Canada (though Canada also uses L/100 km).
L/100 km (fuel per distance)
Measures how much fuel you consume per 100 km of travel. Lower is better — 6 L/100 km is more efficient than 10 L/100 km. Standard in continental Europe, Australia, and most of Asia.
To convert between them, use the relationship: L/100 km = 235.21 ÷ MPG. So a 30-MPG car is approximately 7.84 L/100 km. Use our unit converter for quick cross-unit checks, or switch the toggle at the top of this calculator to work in whichever system your vehicle specs use.
How to lower fuel costs
Reducing the amount you spend on fuel comes down to either using less of it per kilometre or paying less per litre — and ideally both. The tips below address the first lever, which is entirely in your control.
- •Drive smoothly. Aggressive acceleration and hard braking can reduce fuel economy by 15–30% in city driving. Accelerate gently and anticipate stops so you coast rather than brake.
- •Keep tires properly inflated. Under-inflated tires increase rolling resistance. The US Department of Energy estimates that for every 1 PSI drop in tire pressure across all four tires, fuel economy falls by about 0.2%. Check monthly.
- •Remove unnecessary weight. An extra 100 lb (45 kg) in the trunk reduces fuel economy by roughly 1–2%. Remove roof racks, cargo carriers, and heavy items you are not using.
- •Combine errands into one trip. A cold engine uses more fuel than a warm one. Running five short separate errands burns significantly more fuel than chaining them into a single loop. Plan routes to avoid backtracking.
- •Keep up with engine maintenance. A poorly tuned engine — dirty air filter, worn spark plugs, low oil — can reduce fuel economy by 4% or more. Regular servicing pays for itself in fuel savings on high-mileage vehicles.
- •Mind your speed on the highway. Aerodynamic drag increases with the square of speed. Most vehicles reach peak fuel efficiency between 45–55 mph. Driving at 70 mph rather than 55 mph can cut fuel economy by 17%, which directly inflates the cost estimate above.
If you are also curious about the cost of charging an electric vehicle for comparison, see our electricity cost calculator. And if gas prices are listed in a foreign currency, our currency converter can convert them to your home currency before you enter them here.
❓Fuel cost calculator — frequently asked questions
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