Planning a road trip, daily drive, or weekend visit usually starts with one practical question: how much will the fuel cost? The answer depends on your trip distance, your vehicle’s fuel efficiency, and the price of gas or petrol.
Use the fuel cost calculator below to estimate how much fuel you may need, your total trip cost, and the fuel cost per mile or kilometre. It supports miles, kilometres, US and UK MPG, kilometres per litre, and litres per 100 kilometres, so you can use the measurements that match your vehicle and location.
Estimate Your Trip Fuel Cost
Enter your trip details to estimate the fuel required, total fuel cost, cost per mile or kilometre, and cost per person.
No additional budget buffer has been added.
How to Use the Fuel Cost Calculator
Use these steps to estimate how much fuel your trip may require and what it may cost:
- Enter the trip distance. Add the distance for one leg of the journey and choose miles or kilometres.
- Choose one way or round trip. The calculator automatically doubles the main distance when you select “Round trip.”
- Add extra driving if needed. Include expected detours, local driving, sightseeing, or additional stops that are not included in the main route distance.
- Enter your vehicle’s fuel efficiency. Choose MPG (US), MPG (UK), kilometres per litre, or litres per 100 kilometres. Use a realistic figure based on the type of driving you expect.
- Add the fuel price. Enter the expected price per US gallon, Imperial gallon, or litre. A current local price or reasonable route average usually provides a better estimate.
- Choose your currency and budget buffer. The buffer is optional, but it may help you plan for traffic, changing fuel prices, or minor route changes.
- Enter the number of people sharing the cost. Leave this set to one when you are paying the full fuel cost yourself.
The calculator will show the estimated fuel cost, fuel required, total driving distance, fuel cost per mile or kilometre, cost per person, and a suggested budget that includes your selected buffer.
How to Calculate Fuel Cost for a Trip
To estimate the fuel cost for a trip, first calculate how much fuel the vehicle may use. Then multiply that amount by the expected fuel price.
The exact formula depends on whether your vehicle displays fuel efficiency as MPG, kilometres per litre, or litres per 100 kilometres.
Formula Using MPG
When fuel efficiency is measured in miles per gallon:
Fuel needed = Trip distance ÷ MPG
Fuel cost = Fuel needed × Price per gallon
For example, a 300-mile trip in a vehicle that gets 30 MPG would require:
300 ÷ 30 = 10 gallons
If gas costs $3.50 per gallon:
10 × $3.50 = $35
The estimated fuel cost would be $35.
Make sure the gallon type matches the MPG figure. Use US gallons with MPG (US) and Imperial gallons with MPG (UK).
Formula Using Kilometres per Litre
When fuel efficiency is measured in kilometres per litre:
Fuel needed = Trip distance ÷ Kilometres per litre
Fuel cost = Fuel needed × Price per litre
For example, a vehicle that travels 15 kilometres per litre over a 450-kilometre trip would use:
450 ÷ 15 = 30 litres
If fuel costs $1.60 per litre:
30 × $1.60 = $48
The estimated fuel cost would be $48.
Formula Using Litres per 100 Kilometres
When fuel consumption is shown as litres per 100 kilometres:
Fuel needed = Trip distance × L/100 km ÷ 100
Fuel cost = Fuel needed × Price per litre
For example, a vehicle rated at 7.5 L/100 km over a 400-kilometre trip would use:
400 × 7.5 ÷ 100 = 30 litres
If fuel costs $1.70 per litre:
30 × $1.70 = $51
The estimated fuel cost would be $51.
How to Calculate Fuel Cost per Mile or Kilometre
Fuel cost per mile or kilometre shows how much you are spending on fuel for each unit of distance.
Fuel cost per mile or kilometre = Total fuel cost ÷ Total trip distance
For example, if a 300-mile trip costs $35 in fuel:
$35 ÷ 300 = about $0.12 per mile
This figure covers fuel only. It does not include maintenance, insurance, depreciation, parking, tolls, or other vehicle expenses.
Which Fuel-Efficiency Number Should You Enter?
The fuel-efficiency figure you enter can make a noticeable difference to the estimate. Choose the number that best matches the type of driving expected during the trip.
Highway MPG
Use highway MPG when most of the journey involves steady driving on highways or motorways with limited stopping.
Highway fuel economy is usually better than city fuel economy because the vehicle spends less time idling, braking, and accelerating. However, very high speeds, heavy traffic, steep roads, or additional cargo may reduce the actual result.
City MPG
Use city MPG when the trip mainly involves urban roads, frequent traffic lights, stop-and-go traffic, or short journeys.
City MPG is usually lower than highway MPG, so it may provide a more realistic estimate for driving within towns or busy metropolitan areas.
Combined MPG
Use combined MPG when the journey includes a meaningful mix of city and highway driving.
This is often the most practical choice when you are unsure how much of the route will fall into each type. It provides a middle estimate rather than assuming ideal highway conditions.
Your Recent Fuel-Economy Average
Your vehicle’s recent real-world average may provide a more personalized estimate than its advertised rating.
If you are in the US and do not know your vehicle’s official rating, you can look up model-specific fuel-economy information through FuelEconomy.gov.
You may find this figure on the dashboard, trip computer, fuel-economy display, or records from previous fill-ups. Use an average from similar driving conditions when possible.
For example, a recent highway average may be more useful for a long road trip than an average based mostly on short city journeys.
Tip
When you are unsure which figure to use, choose the more conservative fuel-efficiency estimate. A slightly lower MPG or km/L figure may help reduce the chance of underestimating your fuel budget.
How to Get a More Realistic Trip Estimate
A fuel cost calculator gives you a useful starting point, but the result is only as accurate as the information you enter. A few small adjustments may make the estimate more practical for real-world travel.
Include the Return Journey
Make sure the calculator reflects the full distance you expect to drive.
Use the “Round trip” option when you plan to return to your starting point. Do not enter the total round-trip distance and select “Round trip” at the same time, or the calculator will count the return journey twice.
Add Local Driving and Planned Stops
Your main route may not include every mile or kilometre you drive during the trip.
Consider adding extra distance for:
- driving around the destination
- planned sightseeing
- fuel or meal stops away from the route
- getting to and from accommodation
- minor detours
Use the “Extra driving” field rather than increasing the main trip distance without explanation.
Use a Realistic Fuel Price
Fuel prices may differ between your starting area, the route, and the destination. The cheapest local station may not represent what you will pay throughout the trip.
You may get a more useful estimate by entering:
- a recent local price
- an average of prices along the route
- a slightly higher figure for cautious budgeting
A gas-saving or fuel-price app may help you compare nearby prices, find available rewards, and choose a more realistic fuel price before filling up.
Add a Budget Buffer
A budget buffer gives you a separate planning figure above the basic fuel estimate.
For example, if the calculated fuel cost is $80, a 10% buffer would produce a suggested fuel budget of $88.
The buffer does not mean the trip will automatically use more fuel. It simply leaves room for changing prices, traffic, small detours, or lower-than-expected fuel efficiency.
Why Your Actual Fuel Cost May Be Different
The calculator provides an estimate based on the distance, fuel efficiency, and fuel price you enter. Your actual trip cost may differ because real-world driving conditions are rarely identical to the assumptions used in the calculation.
The US Department of Energy’s efficient-driving guidance explains that idling, speeding, frequent acceleration or braking, improper gear shifting, and indirect routes may reduce fuel economy.
Factors that may affect fuel use include:
- heavy traffic and idling
- frequent acceleration and braking
- higher driving speeds
- cold weather or strong winds
- steep roads or difficult terrain
- air-conditioning use
- additional passengers or cargo
- roof racks or external carriers
- low tire pressure
- route changes or unexpected detours
- changing fuel prices during the trip
Your vehicle may also use more or less fuel than its advertised MPG or consumption rating. Using a recent real-world average and adding a modest budget buffer may provide a more practical estimate.
What the Fuel Cost Estimate Includes and Excludes
The calculator focuses specifically on the fuel required for the trip. It does not estimate the full cost of owning a vehicle or taking a road trip.
What the Estimate Includes
The calculation may include:
- the main trip distance
- the return journey when “Round trip” is selected
- optional extra driving
- your vehicle’s fuel-efficiency figure
- the fuel price you enter
- the cost per mile or kilometre
- the cost per person when the expense is shared
- an optional budget buffer
The budget buffer is shown separately from the estimated fuel cost, so you can distinguish the calculated amount from the amount you may choose to set aside.
What the Estimate Does Not Include
The result does not include:
- tolls
- parking
- food or accommodation
- rental-car charges
- maintenance and repairs
- tires
- insurance
- registration fees
- depreciation
- loan or lease payments
- business mileage reimbursement
- electric-vehicle charging costs
These expenses may still be part of your overall travel or transportation budget, but they are not fuel costs. A trip with an estimated fuel cost of $60 may therefore cost more once tolls, parking, meals, or other expenses are added.
For monthly planning, fuel, parking, public transit, and other car-related costs generally belong in the transportation section of your budget.
Plan Your Fuel Budget Before You Leave
A fuel cost estimate may help you prepare for a trip without relying on guesswork. For a more realistic result, use the full driving distance, a recent fuel-efficiency figure, and a fuel price that reasonably reflects the route.
The final amount may still vary, so consider leaving a little room in your budget for traffic, detours, or changing fuel prices.
Frequently Asked Questions About Trip Fuel Costs
How do I calculate gas cost for a trip?
Divide the total trip distance by your vehicle’s fuel efficiency to estimate the fuel needed. Then multiply the fuel needed by the price per gallon or litre.
For example, a 240-mile trip in a vehicle that gets 30 MPG would require about 8 gallons. At $3.50 per gallon, the estimated gas cost would be $28.
How much gas will I need for a 500-mile trip?
The amount depends on your vehicle’s MPG.
A vehicle that gets 25 MPG would use about 20 gallons for a 500-mile trip. A vehicle that gets 40 MPG would use about 12.5 gallons.
Use your vehicle’s realistic fuel-efficiency figure for a more useful estimate.
How do you calculate fuel cost per mile?
Divide the total fuel cost by the total distance driven.
For example, if you spend $48 on fuel for a 400-mile trip:
$48 ÷ 400 = $0.12 per mile
This figure represents fuel cost only, not the full cost of driving.
Should I use city, highway, or combined MPG for a trip?
Use highway MPG when most of the route involves steady highway driving. Use city MPG for mainly urban or stop-and-go driving. Combined MPG is usually the better choice when the journey includes both city and highway driving.
How do I calculate gas cost for a round trip?
Double the one-way distance before calculating the fuel needed, or select the calculator’s “Round trip” option. For example, a destination 180 miles away creates a total driving distance of 360 miles when you return to the starting point.
What is the difference between US MPG and UK MPG?
US MPG is based on a US gallon, which equals approximately 3.785 litres. UK MPG uses an Imperial gallon, which equals approximately 4.546 litres, according to NIST conversion standards. Because an Imperial gallon is larger, the same vehicle may show a higher numerical MPG figure under the UK system.
How do I split gas cost between passengers?
Divide the total estimated fuel cost by the number of people sharing the expense.
For example, if the fuel cost is $72 and four people are splitting it equally:
$72 ÷ 4 = $18 per person
For a group trip, a bill-splitting app may also help you record fuel, tolls, parking, and other shared expenses.
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