Diesel vs Gasoline Converter

Understanding Fuel Energy Equivalents

Diesel and gasoline contain different amounts of energy per gallon. A gallon of diesel fuel contains approximately 13% more energy than a gallon of gasoline, which is why diesel engines tend to get better fuel economy on a per-gallon basis. Fuel equivalents allow fair comparisons between different fuel types by normalizing them to the same energy content.

Energy Content of Common Fuels:

Key Conversion Formulas:

Diesel Gallon Equivalent (DGE): The amount of an alternative fuel that has the same energy content as one gallon of diesel.

DGE = fuel volume × (fuel BTU per gallon / 129,500)

Gasoline Gallon Equivalent (GGE): The amount of an alternative fuel that has the same energy content as one gallon of gasoline.

GGE = fuel volume × (fuel BTU per gallon / 114,000)

Diesel to Gasoline Conversion:

1 gallon diesel = 1.136 gallons gasoline (energy equivalent) 1 gallon gasoline = 0.880 gallons diesel (energy equivalent)

This means if you drive a vehicle that gets 30 MPG on gasoline, the diesel equivalent would be approximately 30 × 0.880 = 26.4 miles per gallon of diesel for the same energy consumption. However, diesel engines are typically 20-35% more thermally efficient than gasoline engines, which is why real-world diesel MPG is often higher despite the different energy content.

Cost per BTU Comparison:

To fairly compare fuel costs: Cost per 100,000 BTU = (price per gallon / BTU per gallon) × 100,000

Practical Examples:

• Diesel costs $3.50/gallon and gasoline costs $3.00/gallon. Per 100,000 BTU: diesel = $2.70, gasoline = $2.63. In this scenario, gasoline is slightly cheaper per unit of energy.
• A diesel truck gets 25 MPG. The GGE-equivalent fuel economy is 25 × 1.136 = 28.4 MPGe, making it more comparable to a gasoline vehicle rated at 28 MPG.
• Converting a fleet from gasoline to diesel: if vehicles currently use 1,000 gallons of gasoline per month, they would need approximately 880 gallons of diesel per month for the same energy.

Tips:

• MPG comparisons between diesel and gasoline vehicles are misleading without accounting for the different energy densities.
• The EPA uses GGE (gasoline gallon equivalent) for electric vehicles: 1 GGE = 33.7 kWh of electricity.
• Diesel fuel is denser than gasoline (about 7.1 lb/gallon vs 6.1 lb/gallon), contributing to its higher energy content per volume.
• Fuel prices vary by region and season. Always compare cost per BTU rather than cost per gallon for true economic comparison.