MPG Comparison Calculator
Compare annual fuel cost for two vehicles from MPG, miles driven, and gas price.
Returns yearly savings, 5-year savings, and break-even on efficient upgrades.
MPG comparison between two vehicles calculates the real annual fuel cost difference, helping buyers and drivers make data-driven decisions about fuel economy.
The core formulas:
Annual Fuel Cost = (Annual Miles / MPG) × Price per Gallon
Annual Savings = Annual Cost (Vehicle A) − Annual Cost (Vehicle B)
Payback Period = Price Difference / Annual Savings
5-Year Fuel Cost = Annual Fuel Cost × 5
What each variable means:
- Annual Miles: how far you drive per year (US average: 12,000–15,000 miles)
- MPG: miles per gallon for each vehicle under your typical driving conditions
- Price per Gallon: current local fuel price; use a 5-year average for long-term comparisons
- Payback Period: how long the fuel savings take to offset a higher purchase price
Worked example: Vehicle A: 28 MPG, priced at $28,000. Vehicle B: 42 MPG, priced at $34,000. Annual miles: 14,000. Gas price: $3.50/gallon.
Annual cost A = (14,000 / 28) × $3.50 = 500 × $3.50 = $1,750/year Annual cost B = (14,000 / 42) × $3.50 = 333.3 × $3.50 = $1,167/year Annual savings = $1,750 − $1,167 = $583/year Price difference = $34,000 − $28,000 = $6,000 Payback period = $6,000 / $583 = 10.3 years
Key insight: The payback period exceeds the typical 7–8 year ownership period in this example. However, at $4.50/gas or 20,000 miles/year, payback drops to under 5 years — always run the numbers for your specific situation.
EPA ratings are tested under ideal conditions; real-world MPG is typically 15–25% lower.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.