Everyday Tools
Fuel Cost Calculator
Work out how much fuel a trip burns and what it costs, with an optional round-trip and passenger split.
Calculation inputs
Fuel economy is entered in miles per gallon.
Results
No result yet
Complete the fields and select Calculate to show results here.
About this calculator
This tool estimates how much fuel a trip will use and what it will cost, based on distance, your vehicle's fuel economy, and the price of fuel. Drivers use it to budget road trips, compare routes, or split costs with passengers.
How the calculation works
- Gallons needed = distance ÷ miles per gallon
- Total cost = gallons needed × price per gallon
- A round trip doubles the distance before the fuel calculation
Notes and assumptions
Real-world economy drops with highway speed, roof loads, towing, and cold weather.
How it works in plain English
The calculator starts with the distance you plan to drive and divides it by your vehicle's fuel economy in miles per gallon, which gives the number of gallons the trip is expected to burn. This is simply the inverse relationship between how far a vehicle travels and how efficiently it uses fuel per gallon.
Multiplying the gallons needed by the price per gallon gives the total dollar cost of fuel for the trip. If you select a round trip, the distance is doubled before this calculation runs, since the vehicle covers the same route twice.
The results also break the cost down per mile and per 100 miles, which makes it easier to compare trips of different lengths or different vehicles on an even footing, and divide the total cost evenly among any number of people sharing the trip, useful for carpools or shared road trips.
The formula
- Gallons needed = total distance ÷ miles per gallon
- Total fuel cost = gallons needed x price per gallon
Worked example
Suppose you are driving 250 miles one way in a car that gets 28 miles per gallon, with fuel priced at $3.45 per gallon, and you plan to drive back the same day. The round-trip distance is 500 miles. Dividing 500 by 28 gives about 17.9 gallons needed, and multiplying that by $3.45 comes to roughly $61.61 in total fuel cost. Split evenly between three people riding along, that works out to about $20.54 each, or about $0.12 per mile. If gas prices rise to $3.89 per gallon before the trip, the same 17.9 gallons instead costs about $69.63 total, raising each rider's share to roughly $23.21, showing how much a modest price swing can affect a shared road trip budget even when the distance and vehicle stay identical.
Frequently asked questions
Does this account for highway versus city driving?
No, it uses a single fuel economy figure you provide. Real fuel economy varies with highway versus city driving, speed, terrain, and load, so use an average or trip-specific mpg figure from your vehicle's dashboard or owner's manual for a more accurate estimate.
Where can I find my vehicle's fuel economy?
Your dashboard trip computer often displays real-time or average mpg, or you can calculate it yourself by dividing miles driven by gallons used at your next fill-up. The window sticker or manufacturer specs also list official EPA estimates for city and highway driving.
Why does the calculator ask about round trips separately?
A round trip simply doubles the one-way distance before running the fuel math, since the vehicle covers the route there and back. Entering the trip as one-way and remembering to double it manually is an easy step to forget, so the option handles it automatically.
Does fuel price vary enough to matter for planning?
Yes, fuel prices can shift noticeably by region and over time, sometimes by 20 percent or more within the same state. Checking a current local price before a long trip gives a more accurate cost estimate than using a national average.
How is the litres figure useful if I'm using gallons?
The litres conversion is included for reference if you are comparing against a metric fuel economy figure, planning travel in a country that sells fuel by the litre, or simply prefer thinking in metric units for consistency.