Road Trip Gas Cost Calculator
Estimate fuel cost for a road trip. Enter distance, your car's MPG, and gas price to get total gallons, cost, and the cost split per person, instantly.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the steps
How the Road Trip Gas Cost Calculator Works
Planning a drive and want to know the fuel bill before you leave? Enter the trip distance, your vehicle’s MPG, the local gas price, and how many people are splitting the cost. The tool shows the fuel needed, the total cost, and the cost per person.
How it works
Fuel cost depends on three numbers — how far you drive, how efficient your car is, and what gas costs:
Gallons needed = distance ÷ MPG Total cost = gallons × price per gallon Cost per person = total cost ÷ number of people
Worked Example
For a 500-mile trip in a car that gets 28 MPG, with gas at $3.50/gallon, split between 2 people:
- Gallons = 500 ÷ 28 = 17.9 gallons
- Total cost = 17.9 × 3.50 = $62.50
- Per person = 62.50 ÷ 2 = $31.25
How MPG Changes the Bill
| MPG | Gallons for 500 mi | Cost at $3.50/gal |
|---|---|---|
| 20 | 25.0 | $87.50 |
| 28 | 17.9 | $62.50 |
| 35 | 14.3 | $50.00 |
| 45 | 11.1 | $38.89 |
A more efficient vehicle can cut your fuel bill nearly in half over the same route.
Tips for a Better Estimate
- Use round-trip distance. Double the one-way miles if you are coming back the same way.
- Match MPG to the terrain. Drop your number for mountainous or stop-and-go routes.
- Check current prices en route. Gas can be much cheaper just off the highway than at interstate exits.
Frequently asked questions
How do I calculate gas cost for a road trip?+
Divide your trip distance by your car's miles per gallon to get the gallons of fuel needed, then multiply by the price per gallon. For a 500-mile trip at 28 MPG and $3.50/gallon, you need about 17.9 gallons costing roughly $62.50.
How do I find my car's MPG?+
Check the EPA combined rating on the window sticker or manufacturer's site, or measure it yourself: fill the tank, drive, refill, then divide the miles driven by the gallons added. Use your real-world number for the most accurate estimate.
Should I use city or highway MPG for a road trip?+
Road trips are mostly highway driving, so the highway or combined MPG is usually closest. If your route has lots of stops, traffic, or mountains, use a slightly lower number to be safe.
How do I split gas costs fairly between passengers?+
Divide the total fuel cost by the number of people sharing the ride. This calculator does it automatically when you enter the number of people, giving an equal per-person share for the trip.
Does this include the return trip?+
Only if you enter the round-trip distance. For an out-and-back journey, double the one-way mileage before entering it so the cost covers both directions.