Diesel vs Gasoline Converter
Convert between diesel gallon equivalents (DGE), gasoline gallon equivalents (GGE), and energy content in BTU for fuel comparison.
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1 gal gasoline = 114,000 BTU = 33.4 kWh
1 gal diesel = 129,500 BTU = 37.9 kWh
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:
| Fuel Type | Energy per Gallon (BTU) | Energy per Liter (BTU) |
|---|---|---|
| Gasoline (regular) | 114,000 BTU | 30,113 BTU |
| Diesel (No. 2) | 129,500 BTU | 34,207 BTU |
| E85 (85% ethanol) | 83,000 BTU | 21,926 BTU |
| Biodiesel (B100) | 119,550 BTU | 31,578 BTU |
| Propane (LPG) | 84,250 BTU | 22,257 BTU |
| CNG (per GGE) | 114,000 BTU | — |
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.