How to Calculate Fuel Cost for a Road Trip

To estimate fuel cost for a road trip, calculate how much fuel the journey will use, then multiply by the pump price. In metric units, that means distance in kilometres × L/100 km ÷ 100 × price per litre. A 750 km trip at 7.8 L/100 km and CAD1.72/L uses 58.5 litres and costs CAD100.62 in fuel.

For miles and U.S. MPG, divide the distance by MPG, then multiply by the price per U.S. gallon. Below, we work through both systems, return journeys, shared bills and the assumptions that can change your budget. All prices and vehicle-efficiency figures in the examples are hypothetical, rather than current averages or ratings for a specific model.

Have your distance and vehicle consumption ready? The Trip Fuel Cost Calculator works out the fuel bill, fuel needed and cost per person using your own inputs.

In this guide

• Choose your distance, efficiency and fuel price
• Use the metric or U.S. formula
• Canadian and return-trip example
• U.S. example using miles and MPG
• Compare fuel prices and efficiency
• Handle different driving conditions
• Split fuel and other shared expenses
• Improve your estimate before leaving

Start with three inputs

1. Road distance. Use the distance along your planned route, including stops and detours, rather than the straight-line distance between cities. Check whether your mapping app shows one direction or the entire itinerary.
2. Fuel efficiency. Use a relevant L/100 km or U.S. MPG figure for your vehicle. Recent records from similar driving are useful; otherwise, start with the rating for the correct model year, engine, transmission and drivetrain.
3. Fuel price. Enter the price for the fuel grade you will buy, in the same volume units as your calculation. A price per litre cannot be used directly with a miles-per-gallon calculation.

A Canadian combined consumption rating reflects 55% city and 45% highway driving, according to Natural Resources Canada. Your road trip may have a different mix. A highway rating can inform a highway-heavy estimate, but it is not a guarantee of what a loaded vehicle will achieve in traffic or winter conditions.

The fuel-cost formulas

Kilometres, litres and L/100 km

Fuel needed in litres = total kilometres × L/100 km ÷ 100

Fuel cost = litres needed × price per litre

Lower L/100 km means less fuel used for the same distance. Keep the fuel price in CAD/L, USD/L or another clearly identified currency per litre; the arithmetic is the same.

Miles, U.S. MPG and U.S. gallons

Fuel needed in U.S. gallons = total miles ÷ U.S. MPG

Fuel cost = U.S. gallons needed × price per U.S. gallon

Higher MPG means less fuel used for the same distance. The U.S. Department of Energy and EPA use the equivalent calculation for fuel cost per 100 miles. Check which gallon your figure uses: imperial MPG and U.S. MPG are different. Our calculator uses U.S. gallons in its miles setting.

Canadian example: a 750 km journey and the return trip

Suppose the outward journey is 750 km, expected consumption is 7.8 L/100 km, and gasoline costs CAD1.72/L. These are example assumptions, not a quoted route or current pump price.

Fuel needed: 750 × 7.8 ÷ 100 = 58.5 litres. Fuel cost: 58.5 × CAD1.72 = CAD100.62.

Journey	Fuel needed	Fuel cost
750 km one way	58.5 L	CAD100.62
1,500 km return	117 L	CAD201.24

If four people share the return fuel bill equally, CAD201.24 ÷ 4 = CAD50.31 per person. Include the driver in the number of people if they are paying an equal share.

Avoid doubling the distance twice. In the calculator, enter 750 km and select Return trip. Entering 1,500 km and then selecting Return trip would calculate 3,000 km. If the return route is different, estimate the two directions separately and add their fuel costs.

U.S. example: 420 miles at 28 MPG

For a 420-mile outward journey, 28 U.S. MPG and a hypothetical USD3.65 per U.S. gallon:

• Fuel needed: 420 ÷ 28 = 15 U.S. gallons.
• One-way fuel cost: 15 × USD3.65 = USD54.75.
• Return distance of 840 miles: 30 gallons and USD109.50, with the same assumptions.
• Return fuel cost shared equally by three people: USD36.50 each.

The Canadian and U.S. examples are separate scenarios. They do not compare national fuel prices, and the amounts have not been converted between currencies. Selecting USD or CAD in the calculator changes the currency label; it does not apply an exchange rate.

How fuel prices and efficiency change your budget

A single estimate can look more precise than its inputs justify. For a 900 km total itinerary, the table below shows what happens when consumption and pump prices change. All amounts are CAD and all inputs are hypothetical.

L/100 km	CAD1.50/L	CAD1.75/L	CAD2.00/L
6	81.00	94.50	108.00
8	108.00	126.00	144.00
10	135.00	157.50	180.00

For example, 900 km at 8 L/100 km uses 72 litres. At CAD1.75/L the bill is CAD126.00; at CAD2.00/L it is CAD144.00. The vehicle and distance are unchanged, but the pump-price assumption adds CAD18.00.

You can also test a price change directly: extra cost = litres needed × change in price per litre. In the earlier 750 km example, 58.5 litres × CAD0.10/L adds CAD5.85. Use the trip fuel calculator to compare assumptions for your own journey.

Calculate different driving conditions separately

One average works when it reasonably describes the whole journey. If one part involves open roads and another involves slower traffic, calculate each leg with its own consumption figure.

For an illustrative 1,200 km itinerary at CAD1.70/L:

• First 600 km at 6.5 L/100 km: 39 litres and CAD66.30.
• Next 600 km at 9.0 L/100 km: 54 litres and CAD91.80.
• Total: 93 litres and CAD158.10.

The overall consumption is 93 ÷ 1,200 × 100 = 7.75 L/100 km. Averaging 6.5 and 9.0 happens to work here because the distances are equal. For unequal distances, add the litres first, then divide by the total distance and multiply by 100.

Do not average MPG figures directly. Driving 210 miles at 20 MPG uses 10.5 gallons; another 210 miles at 40 MPG uses 5.25 gallons. The combined result is 420 ÷ 15.75 = 26.67 MPG, rather than 30 MPG. Total distance divided by total gallons gives the correct figure.

For a cross-border journey, estimate each leg using matching units and its local fuel price. Convert the resulting monetary amounts to one currency using your chosen exchange rate before adding them. Keep that conversion separate from the calculator’s currency selector.

Fuel consumed, pump receipts and your shared trip budget

The fuel estimate values the fuel consumed during the journey. Your spending at petrol stations during that same period can differ if you start with fuel already in the tank or finish with a different fuel level. Agree whether a group is sharing the estimated fuel consumed or settling actual purchases with an adjustment for the starting and ending tank levels.

Fuel is also only one part of a shared travel budget. Using the Canadian return-trip example, suppose the group agrees to share these additional hypothetical expenses:

Shared expense	Return-trip total
Fuel	CAD201.24
Tolls	CAD24.00
Parking	CAD36.00
Total shared expenses	CAD261.24

Four equal shares would now be CAD65.31 each, compared with CAD50.31 for fuel alone. Add ferries, a rental charge or other agreed costs when relevant. Food and accommodation need their own budget. The calculator’s cost-per-person result divides fuel only; it does not include these extras.

If people join for different legs or use different cost-sharing arrangements, split the fuel estimate for each relevant leg among the people sharing that leg. A single equal split across the entire itinerary would answer a different question.

If you’re also budgeting for meals, lodging and tolls, see the full road-trip budget guide for Canadian and U.S. examples and a way to split shared expenses.

Improve the estimate before you leave

1. Measure your own consumption when possible. FuelEconomy.gov’s My MPG guidance uses at least two consecutive full-tank purchase records to calculate MPG. Divide distance since the previous full refill by the gallons used to refill; for metric consumption, divide litres used by kilometres travelled and multiply by 100. Keep tank levels comparable by following the vehicle’s normal filling procedure.
2. Match the conditions. Natural Resources Canada explains that weather, speed, traffic, vehicle condition and accessories can affect actual consumption. Use an estimate suited to the journey and test a less favourable scenario instead of applying one universal penalty.
3. Review the load and driving plan. DOE and EPA driving-efficiency guidance identifies aggressive driving, high speeds, roof cargo and unnecessary weight as factors that can increase fuel use. Their effects vary; this guide does not promise a fixed saving from any one change.
4. Recheck the itinerary and prices. Include local driving and detours you actually expect to make. Use a recent price for the required fuel grade, and recalculate if the planned route or assumptions change.

Our calculator expects you to enter a distance. If you need a mapped itinerary with intermediate stops, the official DOE and EPA Trip Calculator offers that alternative. Neither a route estimate nor a published vehicle rating can predict every traffic or weather condition.

Common road-trip fuel questions

How do I calculate fuel cost per kilometre or mile?

For metric inputs, divide L/100 km by 100 and multiply by the price per litre. At 7.8 L/100 km and CAD1.72/L, fuel costs CAD0.13416 per km, or about 13.4 cents/km. For U.S. inputs, divide price per U.S. gallon by U.S. MPG. This is fuel cost per distance, not the full cost of owning and operating a vehicle.

Can I use this for a hybrid or diesel vehicle?

Yes, for its liquid-fuel consumption: use the appropriate consumption figure and the actual fuel price for that vehicle. A plug-in hybrid journey that uses both charging and gasoline needs both energy costs accounted for separately. For an electric vehicle comparison, use the EV vs Gas vs Hybrid Cost Calculator.

How much should I add for unexpected costs?

There is no single correct allowance for every road trip. Test realistic alternative distance, efficiency and price inputs, then set aside a separate amount for uncertain expenses that matter to your itinerary. A higher fuel estimate does not automatically cover parking, a ferry or an overnight stop.

Calculate your own trip fuel budget

Enter your one-way distance, expected fuel efficiency and local pump price. Choose a return journey when appropriate, then add the people sharing fuel costs. Keep a separate list for other travel expenses.

Choosing between vehicles for more than one journey? Read our hybrid vs gas savings guide or compare annual savings in the Hybrid vs Gas Cost Calculator.

Methodology and sources

All worked examples and tables are original calculations by Drive Cost Calculator using the stated hypothetical distances, consumption figures and prices. Calculations retain full precision before monetary results are rounded to cents. Independently rounded shares may not recombine to the exact total. The examples do not establish current fuel prices, route distances or real-world ratings for a named vehicle.

The government sources support the explanations of vehicle ratings, measurement and driving conditions. They are not the source of the example prices or trip scenarios:

• Natural Resources Canada: Understanding fuel consumption ratings.
• Natural Resources Canada: Understanding the tables.
• U.S. DOE and EPA: Driving More Efficiently.
• U.S. DOE and EPA: My MPG Help.
• U.S. DOE and EPA: Trip Calculator.

For more about our approach, see Methodology & Data Sources and About Drive Cost Calculator. Contact us if you spot an error or an assumption that needs clarification.