Fuel Cost Calculator
Estimate fuel needed and trip cost from distance, efficiency, and fuel price.
Estimate how much fuel a trip will use and what it will cost, based on distance, your vehicle's fuel efficiency, and the price of fuel.
How Fuel Cost Calculator Works
The calculator first converts your trip distance to miles if you entered kilometers, then converts your fuel efficiency into gallons used for that distance — the exact method depends on whether efficiency is entered as miles per gallon, kilometers per liter, or liters per 100 km, since each represents the distance-to-fuel relationship differently.
Once gallons used is known, total fuel cost is simply gallons multiplied by the price per gallon you entered. The result is also shown in liters and as a cost-per-distance-unit figure, useful for comparing trip costs across different vehicles.
See It In Action
Who Uses Fuel Cost Calculator and Why
- Budgeting the fuel cost of a road trip before you leave, so gas expenses don't blow past what you set aside.
- Comparing two possible routes to the same destination when one is shorter in distance but involves more highway driving at a different effective efficiency.
- Working out how much a daily commute is really costing per week or month once fuel price and distance are both factored in.
- Estimating fuel costs for a rental or borrowed vehicle whose efficiency you only know from the spec sheet, not personal experience.
Mistakes to Avoid
- Entering an efficiency figure in the wrong unit for the selected dropdown — mixing up L/100 km (where lower is better) with km/L (where higher is better) will throw the cost estimate off substantially.
- Using a single efficiency number for a trip that's mostly stop-and-go city driving when the figure you have is a highway rating, or vice versa — the calculator can't tell the difference, only you can pick the closer figure.
- Forgetting to update the fuel price field before a longer trip that crosses regions or countries where prices differ noticeably from home.
Tips for Best Results
- If your vehicle's manual lists separate city and highway MPG figures, run the calculation twice — once per figure — to get a realistic cost range instead of a single point estimate.
- For a trip that mixes highway and city driving, a blended efficiency figure somewhere between the two published ratings will usually track the real result more closely than either extreme.
Fixing Common Problems
The estimated cost seems much higher than what I actually spent on a similar past trip. — Check that the efficiency unit selected matches what you entered — L/100 km values plugged into a km/L or MPG field (or the reverse) produce results that are off by a large factor, not a small one.
The cost didn't change when I switched the distance unit. — Make sure the efficiency unit was also switched to match — pairing a kilometer distance with a miles-per-gallon efficiency figure gives a technically calculable but meaningless result.
Terms Explained
L/100 km: Liters of fuel consumed per 100 kilometers driven — an inverted efficiency scale where a lower number means better fuel economy, unlike MPG or km/L.
Fuel price: The per-unit cost of fuel (per gallon or per liter, matching your chosen fuel unit) used to convert the trip's fuel quantity into a total dollar estimate.