Gas Mileage Calculator
Calculate your vehicle's fuel efficiency (MPG), cost per mile, and annual fuel expenses. Track your gas mileage to save money.
US average: 12,000-15,000 miles/year
Enter your trip details to calculate fuel efficiency.
How It Works
MPG (Miles Per Gallon) is calculated by dividing the distance traveled by the fuel used: MPG = Miles ÷ Gallons. Fill up your tank, reset your trip odometer, drive normally, then fill up again and record how many gallons it took.
For the most accurate results, fill your tank completely each time and measure over several tankfuls. City and highway driving give very different MPG—your car's window sticker shows estimates for both.
Annual fuel cost is calculated by dividing your yearly miles by your MPG, then multiplying by the gas price. This helps you budget and compare the true cost of different vehicles.
Frequently Asked Questions
Why is my MPG lower than the EPA estimate?
EPA tests are conducted under controlled conditions. Real-world factors that reduce MPG include: aggressive driving, excessive idling, heavy loads, roof racks, cold weather, hilly terrain, and poor maintenance. City driving typically yields 15-20% worse MPG than highway.
How can I improve my gas mileage?
Drive smoothly (accelerate and brake gradually), maintain steady speeds, use cruise control on highways, keep tires properly inflated, remove excess weight, avoid excessive idling, use the recommended fuel grade, and keep up with maintenance.
Does AC use more gas?
Yes, air conditioning can reduce fuel economy by 5-25% depending on conditions. However, at highway speeds, open windows create drag that may use more fuel than AC. For city driving, windows down is more efficient; on highways, use AC.
Should I use premium gas?
Only if your car requires it. Using premium in a car designed for regular won't improve performance or MPG—you'll just waste money. Check your owner's manual. If it says "required," use premium. If it says "recommended," regular is usually fine.
How does tire pressure affect MPG?
Under-inflated tires increase rolling resistance, reducing fuel economy by about 0.2% for every 1 PSI drop below optimal. Check tire pressure monthly when tires are cold. The correct pressure is on the door jamb sticker, not on the tire itself.