Free Fuel Cost Calculator - How Much Will Gas Cost for Your Trip?

Calculate the exact fuel cost for any road trip or daily commute. Enter your distance, MPG, and gas price to instantly see your total fuel cost, cost per mile, and annual driving costs.

How to Use This Fuel Cost Calculator

This calculator has two modes. Road Trip Calculator lets you enter your trip distance, your vehicle's MPG, and the current gas price to instantly see your total fuel cost, cost per mile, cost per person, and estimated gas stops. Compare Two Vehicles shows you the annual and lifetime fuel cost difference between any two vehicles so you can see the real financial impact of MPG before buying a car.

How to Calculate Fuel Cost for a Road Trip

The formula for fuel cost is straightforward — divide the total miles by your vehicle's MPG to get the gallons needed then multiply by the gas price per gallon.

Total Fuel Cost = (Miles / MPG) x Gas Price Per Gallon

For example a 500-mile trip in a vehicle getting 32 MPG at $3.50 per gallon costs (500 / 32) x $3.50 = 15.6 gallons x $3.50 = $54.69.

For a round trip simply double the one-way distance before calculating.

Where to Find Your Vehicle's MPG

Your vehicle's fuel economy rating is listed in several places. The EPA fuel economy label was on your vehicle's window when it was new and shows city, highway, and combined MPG ratings. You can look up any vehicle's EPA ratings at fueleconomy.gov. Your car's dashboard may display your actual real-world fuel economy in the trip computer. Your actual MPG depends heavily on driving habits, speed, terrain, and vehicle condition.

For this calculator use your combined MPG rating for mixed driving or your highway MPG for long highway trips where you will mostly be cruising at a steady speed.

How MPG Affects Long-Term Costs

The difference in fuel economy between two vehicles has a dramatic impact on lifetime driving costs that most people significantly underestimate when shopping for a car.

The difference between 20 MPG and 30 MPG at 15,000 miles per year at $3.50 per gallon is $875 per year — or $4,375 over five years of ownership. The difference between 25 MPG and 35 MPG is $600 per year. These savings compound over the years you own the vehicle and can easily offset the price difference between two vehicles.

When comparing vehicles use the Compare Two Vehicles tab above to see the true long-term fuel cost impact before making your decision.

Tips to Improve Your Fuel Economy

Slow down on the highway. Fuel economy drops significantly above 55 MPH. Every 5 MPH above 55 reduces fuel economy by approximately 7 to 14 percent. At 70 MPH versus 60 MPH a vehicle that gets 32 MPG effectively gets closer to 28 MPG.

Keep your tires properly inflated. Under-inflated tires increase rolling resistance and can reduce fuel economy by 0.2 to 3 percent per PSI below the recommended pressure. Check your door jamb sticker for the correct tire pressure.

Avoid excessive idling. Idling gets zero MPG. If you will be stopped for more than 30 to 60 seconds it is more fuel efficient to turn the engine off.

Reduce air conditioning use. Running the AC at full blast reduces fuel economy by 5 to 25 percent depending on the vehicle and conditions. On the highway open windows increase aerodynamic drag — at highway speeds AC is often more efficient than open windows.

Maintain your vehicle. A well-maintained vehicle with clean air filters, fresh spark plugs, and proper oil gets better fuel economy than a neglected one.

Current Average Gas Prices

Gas prices vary significantly by state and change daily. As of 2026 the national average hovers around $3.20 to $3.80 per gallon for regular unleaded though prices in California, Hawaii, and other high-cost states regularly exceed $4.50 per gallon. States like Texas, Mississippi, and Louisiana typically have the lowest gas prices in the country.

For the most current gas prices in your area check GasBuddy.com or the GasBuddy app before your trip.

Frequently Asked Questions

How many miles per gallon does the average car get?

The average fuel economy of all vehicles on US roads is approximately 25 to 28 MPG as of 2026. New cars sold in 2026 average closer to 30 to 36 MPG for passenger vehicles. Trucks and large SUVs average 18 to 22 MPG while hybrid vehicles average 45 to 55 MPG and electric vehicles have no gas cost.

How do I find the cheapest gas on my road trip route?

GasBuddy.com and the GasBuddy app show real-time gas prices at stations along any route. The app can also alert you when you are near cheap gas. Buying gas in rural areas or just outside major cities is typically cheaper than buying at freeway exits or in city centers.

Is it worth driving out of my way for cheaper gas?

Usually not unless the savings are significant. Driving 5 miles out of your way to save $0.20 per gallon on a 15-gallon fill-up saves $3.00 but uses approximately 0.3 gallons of gas in the detour — about $1.00 at current prices. The net savings is only $2.00 and it costs you time. Gas price differences of $0.40 or more per gallon can make a detour worthwhile for large fill-ups.

Does cruise control save gas?

Yes — on flat highway driving cruise control typically improves fuel economy by 7 to 14 percent by maintaining a steady speed and avoiding the minor accelerations and decelerations of manual driving. On hilly terrain cruise control can actually reduce fuel economy because it accelerates to maintain speed going uphill.

How much does it cost to drive 1 mile?

At 30 MPG and $3.50 per gallon the fuel cost per mile is $3.50 / 30 = $0.117 or about 12 cents per mile. At 20 MPG and the same gas price the cost is $0.175 or about 18 cents per mile. The IRS standard mileage rate for 2026 is 67 cents per mile which accounts for fuel, maintenance, insurance, and depreciation — not just gas.

Fuel cost estimates are based on the information you enter and assume consistent driving conditions. Actual fuel economy varies based on speed, terrain, driving habits, vehicle condition, and temperature. Gas prices fluctuate daily. Check current local prices before your trip.