Gas Trip Cost Calculator
Estimate fuel cost for a road trip from miles, MPG, and price per gallon. Optional round trip and split among passengers.
How to use this gas trip cost calculator
Gas trip cost is gallons times the pump price. Highway MPG is what you want, not the city sticker, unless the trip is stop-and-go. A roof box, headwind, and a loaded SUV can drop MPG 10–20%.
Split evenly only if everyone agrees. Tolls, hotels, and EV charging are not in this number. For work miles paid at the IRS rate, use the Mileage Reimbursement Calculator instead — that is cents per mile, not fuel.
Formula
Worked example
320 miles each way, 28 MPG, $3.45/gal, round trip: 640 ÷ 28 ≈ 22.9 gallons × $3.45 ≈ $78.90.
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Frequently asked questions
How much does a 500-mile trip cost in gas?
Gallons = 500 ÷ your MPG, then multiply by $/gallon. At 30 MPG and $3.50, about $58 one way.
Should I use highway or combined MPG?
Highway for a cruise; combined if you have city on both ends.
Round trip?
Toggle yes to double the miles. Return traffic can use more fuel than the outbound.
Can I split with passengers?
Enter people splitting. This is even split, not by weight or who drove.
Does this work for EVs?
Use kWh and $/kWh in your head, or treat MPG as MPGe only as a rough comparison.
Results are estimates for informational purposes and are not financial, legal, or professional advice. Last reviewed 2026-08-20.