Gas vs Diesel Cost Calculator

How it works

Annual fuel cost = miles ÷ MPG × price per gallon · Savings = |gas cost − diesel cost|

Each side turns a year of driving into a fuel bill: divide the annual miles by the fuel economy to get the gallons burned, then multiply by the pump price. Diesel usually wins on fuel economy — often 20–30% better than a comparable gas engine — but diesel fuel typically costs more per gallon, so the comparison hinges on whether the mileage advantage outweighs the price premium. This looks at fuel only; diesels also tend to carry higher purchase prices and pricier scheduled maintenance (and DEF), while often holding value and lasting longer, so weigh those against the fuel numbers here.

Worked example

Driving 15,000 miles a year: a 25 MPG gas car at $3.50/gal burns 600 gallons for $2,100. A 32 MPG diesel at $4.00/gal burns 468.75 gallons for $1,875. Diesel is cheaper by about $225 a year, or roughly $1,125 over five years — before factoring in purchase price and upkeep.

Frequently asked questions