Gasoline Gallon Equivalent Calculator

A gasoline gallon equivalent (GGE) calculator converts the amount of an alternative fuel (like natural gas, propane, or electricity) into the amount of gasoline that contains the same energy. You enter the quantity and type of fuel, and the calculator returns the GGE value based on the lower heating value of each fuel. This lets you compare fuel costs and consumption across different energy sources on a common basis.

Formula

The basic formula is straightforward: GGE = quantity of fuel × GGE factor for that fuel. The GGE factor is the ratio of the lower heating value (LHV) of gasoline to the LHV of the alternative fuel. In symbols:

GGE = Q × (LHV_gasoline / LHV_fuel)

Where:

• Q = volume or mass of the alternative fuel (gallons for liquids, pounds for gases, kWh for electricity)
• LHV_gasoline = 114,000 BTU per gallon (standard value used by the U.S. Department of Energy)
• LHV_fuel = lower heating value of the specific fuel per its usual unit

For example, propane has an LHV of about 83,500 BTU per gallon, so its GGE factor is 114,000 / 83,500 ≈ 1.37. That means 1 gallon of propane contains the same energy as 0.73 gallons of gasoline (1 / 1.37). The calculator above uses these fixed factors for simplicity, but you can also compute a custom factor if you have exact LHV data.

Worked Example

Using the default values from the calculator: 100 gallons of gasoline (fuel type set to Gasoline, factor = 1).

1. Multiply the quantity by the factor: 100 × 1 = 100 GGE.
2. Energy content: 100 × 1 × 114,000 = 11,400,000 BTU.

The result is 100.00 GGE, which makes sense because gasoline compared to itself has a 1:1 ratio. If you change the fuel type to propane (factor 1.37), then 100 gallons of propane gives 137 GGE, meaning it has 37% more energy than 100 gallons of gasoline. The energy content would be 15,618,000 BTU.

Why Use GGE?

The whole point of the GGE is to put different fuels on an equal footing. A gallon of propane is not the same as a gallon of gasoline—it has less energy per gallon, so you need more propane to travel the same distance. Similarly, a pound of hydrogen has far more energy per pound than a gallon of gasoline, but it is stored as a compressed gas, so volume comparisons are tricky.

GGE is widely used in fleet management, government reporting, and fuel price comparisons. For instance, if propane costs $2.50 per gallon and gasoline costs $3.00 per gallon, you might think propane is cheaper. But because 1 gallon of propane only gives you 0.73 GGE, the cost per GGE is $2.50 / 0.73 = $3.42, making it more expensive per unit of energy. The GGE calculator helps you make that kind of comparison quickly.

How to Choose the Right Fuel Factor

The calculator includes common fuel types, but you may need to adjust the factor if your fuel blend or measurement unit differs. Here are the key points:

• Gasoline – factor 1.0 by definition.
• E85 – 85% ethanol, 15% gasoline; factor about 1.31 because ethanol has lower energy density.
• Propane – factor 1.37 for LHV.
• CNG (compressed natural gas) – factor 1.47 when measured in gallons of gasoline equivalent, but often sold by the pound or GGE directly.
• LNG (liquefied natural gas) – factor 1.53 per gallon.
• Methanol – factor 2.06.
• Ethanol – factor 1.5 for pure ethanol.
• Hydrogen – factor 8.33 per gallon of liquid hydrogen (but hydrogen is usually measured in kilograms, not gallons).

If your fuel is not listed, look up its lower heating value in BTU per gallon (or per pound for gases) and compute the factor as 114,000 divided by that number. For electricity, the common conversion is 33.7 kWh per GGE, because 1 gallon of gasoline contains about 33.7 kWh of energy. That is not in the calculator above because it uses a different unit (kWh), but you can convert manually.

Common Mistakes and Misconceptions

One frequent error is mixing up lower and higher heating values. The GGE standard uses LHV, which excludes the heat of vaporization of water. Some sources use HHV (higher heating value), which gives different factors—for natural gas, the difference is about 10%. Always check which value your source uses.

Another mistake is comparing volumes without accounting for density. For example, a gallon of propane weighs less than a gallon of gasoline, so if you are comparing by weight, the factors change. The GGE is defined per volume for liquids, but for gases like CNG, it is often per pound or per standard cubic foot. The calculator above assumes you are entering the fuel in gallons (or pounds for hydrogen if you use the factor 8.33 per pound, but that is not standard).

Also, GGE does not account for engine efficiency. An electric motor converts energy to motion more efficiently than a gasoline engine, so 33.7 kWh of electricity may take you further than 1 gallon of gasoline in a typical car. GGE is purely an energy content comparison, not a distance comparison.

Cost Comparisons Using GGE

To compare fuel costs, you need the price per unit of each fuel. The steps are:

1. Calculate the GGE for a given quantity (using the calculator).
2. Divide the total cost by the GGE to get cost per GGE.
3. Compare that number across fuels.

For example, if you buy 100 gallons of propane at $2.50 per gallon, that is $250. The GGE is 137, so cost per GGE = $250 / 137 = $1.82. If gasoline is $3.00 per gallon, cost per GGE is $3.00. In this case, propane is cheaper per unit of energy. But if propane is $3.50 per gallon, cost per GGE = $350 / 137 = $2.55, still cheaper than gasoline. The calculator helps you do these comparisons without manual arithmetic.

Remember that prices vary by region and time, and taxes or subsidies can change the effective cost. Always use current local prices for accurate comparisons.

Limitations of the GGE Calculator

The GGE calculator is a simplification. Real-world fuel properties vary slightly with temperature, pressure, and blend composition. For example, E85 can range from 51% to 83% ethanol depending on season and location, which changes its energy content. The factors used here are standard averages from the U.S. Department of Energy, but they may not match your specific fuel batch.

Also, the calculator only handles energy content, not other factors like engine efficiency, vehicle range, or infrastructure costs. For a complete comparison, you would need to consider the vehicle’s fuel economy in miles per gallon (or MPGe for electric vehicles), which is a separate measure. The GGE is a starting point for understanding the energy equivalence, not the final word on which fuel is better.

Frequently Asked Questions

How many kWh are in a gallon of gasoline?

One gallon of gasoline contains about 33.7 kWh of energy (based on LHV). This is the standard conversion used for electric vehicle comparisons, where you see MPGe (miles per gallon equivalent) ratings.

What is the difference between GGE and MPGe?

GGE measures energy content of a fuel relative to gasoline. MPGe is a fuel economy rating for vehicles, showing how many miles a vehicle can travel on the amount of energy in one gallon of gasoline. MPGe is used for electric and hybrid vehicles, while GGE is used for comparing fuels themselves.

Can I use the GGE calculator for diesel?

Diesel has a slightly higher energy content than gasoline—about 128,000 BTU per gallon. To compare with gasoline, you would use a factor of about 0.89 (114,000 / 128,000). This calculator does not include diesel, but you can compute it manually with that factor.

Why is hydrogen’s GGE factor so high?

Hydrogen has a very high energy content per unit of mass, but its density is extremely low. When measured per gallon of liquid hydrogen, it takes about 8.33 gallons of liquid hydrogen to equal the energy of 1 gallon of gasoline. However, hydrogen is usually measured in kilograms, not gallons, so the factor is rarely used in practice.

Does the calculator account for fuel taxes or subsidies?

No, the calculator only handles energy equivalence. Taxes, subsidies, and other incentives vary by location and time, so you must factor those in separately when comparing costs.

What is the lower heating value of gasoline?

The standard LHV used for GGE calculations is 114,000 BTU per gallon. This is an average value; actual gasoline can vary slightly by blend and season, but 114,000 is the accepted standard for official GGE definitions.

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in qty | Fuel quantity | gal | 100 | 0 | 1000000
sel fuel | Fuel type | Gasoline=1, E85=1.31, Propane=1.37, CNG=1.47, LNG=1.53, Methanol=2.06, Ethanol=1.5, Hydrogen=8.33
out gge | Gasoline gallon equivalent | gal | qty * fuel | 2
out btu | Energy content | BTU | qty * fuel * 114000 | 0