Road Trip Gas Cost: How to Budget for Fuel (With Popular Route Costs)
Gas is the biggest variable cost of any road trip. Here is how to estimate it accurately — plus the actual fuel cost for 10 popular US routes.
The formula for estimating gas cost is deceptively simple: total miles divided by your car's MPG, multiplied by the gas price per gallon. A 600-mile trip in a car that gets 28 MPG at $3.50 per gallon: 600 ÷ 28 × $3.50 = $75. Round trip doubles it to $150. Simple — but most people either skip this calculation entirely or wildly misjudge their car's actual fuel efficiency.
Your Real MPG Is Probably Lower Than You Think
The EPA-rated MPG on your car's window sticker is measured under ideal laboratory conditions — steady speed, no wind, no AC, no hills, perfect tire pressure. Real-world highway driving typically delivers 5-15% less than the EPA highway rating. City driving can be 20-30% worse. A car rated at 30 MPG highway might actually deliver 26-27 MPG on a highway trip with AC running, luggage weight, and speed variations.
The most accurate way to know your actual MPG: fill your tank completely, reset the trip odometer, drive normally until near empty, fill up again, and divide miles driven by gallons purchased. Do this three times and average the results. That number — not the sticker — is what you should use for trip budgeting.
Popular US Route Costs (2026 Estimates)
These assume a car averaging 28 MPG with gas at $3.45/gallon. Your actual cost will vary by vehicle and local gas prices.
Los Angeles to San Francisco (380 miles one way): $47 one way, $94 round trip. New York to Washington DC (225 miles): $28 / $56. Chicago to Detroit (280 miles): $35 / $70. New York to Miami (1,280 miles): $158 / $316. Los Angeles to Las Vegas (270 miles): $33 / $66. New York to Boston (215 miles): $27 / $54. Dallas to Houston (240 miles): $30 / $60. Seattle to Portland (175 miles): $22 / $44. Denver to Albuquerque (450 miles): $56 / $112. Cross-country NYC to LA (2,800 miles): $345 / $690.
When Driving Beats Flying (and Vice Versa)
For solo travelers, flying is almost always cheaper for distances over 400 miles when you factor in time, meals on the road, and vehicle wear. But driving wins decisively for families — one tank of gas carries four people, while four plane tickets cost four times as much. The breakeven point for a family of four is roughly 800-1,000 miles: below that, drive; above that, the time cost of a 14+ hour drive tips toward flying even with the ticket premium.
Calculate your exact trip cost with our gas trip calculator — enter your distance, MPG, gas price, and number of passengers to see the cost per person instantly.