How to Calculate Gas Cost for a Road Trip (With Examples)
The simple formula for a trip’s fuel cost, worked examples for popular U.S. routes and tips to budget a road trip.
Updated October 8, 2026
📊 U.S. national averages · EIA week of Nov 9, 2026
Regular$3.995▼ -0.158 vs prior week
Midgrade$4.608▼ -0.149 vs prior week
Premium$5.013▼ -0.145 vs prior week
Diesel$6.127▼ -0.165 vs prior week
You need three numbers: distance, your car’s MPG and the price per gallon.
Trip cost = miles ÷ MPG × price per gallon
Examples (one way, 28 MPG, $4.35/gal)
| Route | Miles | Gallons | Cost |
|---|---|---|---|
| Los Angeles – Las Vegas | 270 | 9.6 | $42 |
| New York – Washington, DC | 225 | 8.0 | $35 |
| Dallas – Houston | 240 | 8.6 | $37 |
| Chicago – Detroit | 285 | 10.2 | $44 |
Distances are approximate and the price is an example: plug in today’s price from the box above or from your state, and your real MPG, in the trip cost calculator.
Budget tips
- Highway MPG at 75 mph is often well below the window-sticker number.
- Fill up before entering expensive areas (city centers, airports, some interstates).
- Add tolls separately.
Frequently asked questions
How do I find my real MPG?
Use the fill-to-fill method described in how to calculate MPG.
Sources: FuelEconomy.gov – Gas Mileage Tips