Fuel Cost Calculator
Calculate your annual gasoline cost and see how it compounds over years. Enter miles driven per year, MPG and gas price to get cost per mile, annual cost and a multi-year chart.
How to use this tool
- Enter miles driven per year, fuel efficiency, gas price and years in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your fuel cost per year and the full breakdown beneath it.
Gas is often the second-biggest car expense after depreciation. This calculator works out your annual fuel bill from miles driven and MPG, and charts total spend over multiple years so you can see the long-run cost.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Gallons per Year = Miles per Year ÷ MPG
Cost per Year = Gallons per Year × Gas Price ($/gal)
Cost per Mile = Gas Price ÷ MPG
Total Cost = Cost per Year × Years
How it works
The calculator divides annual mileage by fuel efficiency to find yearly fuel consumption in gallons, then multiplies by the price per gallon to get annual cost. A per-mile cost is derived by dividing gas price by MPG directly. A cumulative area chart shows how total fuel spend grows over the selected time horizon. The model assumes constant mileage, efficiency, and gas price across all years.
Worked example
- Gallons per year = 12,000 miles ÷ 30 MPG = 400 gallons.
- Cost per year = 400 gal × $3.50/gal = $1,400.
- Cost per mile = $3.50 ÷ 30 MPG ≈ $0.1167/mile.
- Total over 5 years = $1,400 × 5 = $7,000.
Fuel cost per year: $1,400; Cost per mile: ~$0.1167; Total over 5 years: $7,000
Common mistakes to avoid
- Using the EPA-rated MPG instead of real-world MPG, which is typically 10-20% lower due to driving conditions, traffic, and load.
- Applying a single average gas price over many years without accounting for price volatility, which can significantly affect long-term projections.
- Forgetting that MPG declines as a vehicle ages, meaning fuel costs grow faster than a flat-rate projection suggests.
Key terms
- MPG (Miles Per Gallon)
- A measure of fuel efficiency: how many miles a vehicle can travel on one gallon of gasoline.
- Cost per mile
- Fuel expense for each mile driven, calculated as gas price divided by fuel efficiency (MPG).
- Gallons per year
- Total fuel consumed annually, derived by dividing annual mileage by the vehicle's MPG rating.
- Gas price ($/gal)
- The retail price paid per gallon of gasoline at the pump, which fluctuates with crude oil markets and regional taxes.
- Cumulative fuel cost
- The running total of all fuel expenditure from year 1 through the selected time horizon, shown in the area chart.
Frequently asked questions
- How do I find my MPG?
- Fill your tank, reset the trip odometer, drive normally until nearly empty, fill again and divide miles driven by gallons added. Or check your car's dashboard display if it has a fuel economy readout.
- Can I use this for a fleet or business?
- Yes — multiply your per-vehicle figures by the fleet size, or run each vehicle separately and add the totals.