Road Trip Fuel Cost Calculator
Calculate the total fuel cost for a road trip from distance, MPG, and current fuel price.
How to use this tool
- Enter the total trip distance in miles.
- Enter your vehicle's fuel economy in MPG.
- Enter the current fuel price per gallon.
- The calculator returns gallons required and total fuel cost.
Budget your road trip fuel expense before you leave home.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Gallons needed = Distance (miles) ÷ Fuel economy (MPG)
Fuel cost ($) = Gallons needed × Fuel price ($/gal)
How it works
This calculator finds the total fuel cost for a road trip by first dividing the trip distance by the vehicle's fuel economy to determine how many gallons are required, then multiplying that quantity by the current price per gallon.
The calculation assumes a constant real-world MPG for the entire trip; actual consumption will vary with load, terrain, speed, and vehicle condition.
Worked example
- Gallons needed: 500 miles ÷ 25 MPG = 20.0 gallons
- Fuel cost: 20.0 gal × $3.50/gal = $70.00
A 500-mile trip at 25 MPG and $3.50/gal requires 20.0 gallons and costs $70.00 in fuel.
Common mistakes to avoid
- Using straight-line distance instead of actual driving distance, which can understate fuel cost by 20-40% on indirect routes.
- Forgetting that fuel economy drops at highway speeds above 55 MPH -- many vehicles EPA highway ratings assume 55-60 MPH.
- Not budgeting a 5-10% fuel buffer for detours, traffic, or locating an open gas station.
Key terms
- MPG (Miles Per Gallon)
- The number of miles a vehicle travels per US gallon of fuel, used to calculate total fuel consumption over a given distance.
- Gallons needed
- The estimated quantity of fuel required for the trip, computed as trip distance divided by MPG.
- Fuel price ($/gal)
- The retail price of one US gallon of fuel, used to convert fuel volume into a dollar cost.
- Fuel cost
- The total dollar amount expected to be spent on fuel for the road trip.
Frequently asked questions
- How much will a road trip cost in gas?
- Divide total miles by your MPG to get gallons needed, then multiply by the fuel price. A 500-mile trip at 25 MPG with $3.50/gal costs $70 in fuel.
- How do I find my car's actual MPG?
- Fill up the tank, reset the trip odometer, drive normally until the next fill-up, then divide miles driven by gallons added. Repeat for accuracy.