Three Modes
Calculate MPG: divide miles driven by gallons used. Trip Cost: multiply (distance / MPG) by price per gallon. Compare Vehicles: calculate annual fuel cost for each vehicle and show the annual savings of the more efficient option.
Frequently Asked Questions
Fill up your tank completely and note the odometer reading. Drive normally. At the next fill-up, note the odometer again and how many gallons you added. MPG = miles driven / gallons used. For example, if you drove 350 miles and used 14 gallons: 350/14 = 25 MPG.
Fuel cost = (distance / MPG) x price per gallon. For example, a 300-mile trip in a car getting 30 MPG with gas at $3.50/gallon: (300/30) x 3.50 = $35. This calculator handles the math automatically.
Liters per 100 kilometers (L/100km) is the fuel economy measurement used in Canada, Europe, Australia, and most of the world. Unlike MPG (where higher is better), a lower L/100km means better fuel economy. To convert: MPG = 235.215 / L/100km.
As a general benchmark, the EPA rates cars as fuel efficient if they get over 30 MPG combined. Hybrid vehicles typically achieve 45-55 MPG. Plug-in hybrids can exceed 80 MPGe in electric mode. The average fuel economy of new US passenger vehicles in 2024 was approximately 27 MPG.
The difference between 20 MPG and 30 MPG on 15,000 miles per year at $3.50/gallon is: (15000/20 x 3.50) = $2,625 vs (15000/30 x 3.50) = $1,750, a difference of $875/year. Over 5 years that's $4,375. Fuel economy has a significant impact on vehicle operating costs.
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