Rajan Wilcox
Air-fuel ratio (AFR) is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process. The price of air fuel varies depending on the type of fuel, location, and time. For example, the national average price for jet fuel in the US is $6.29 per gallon, while the price of Jet A1 fuel is approximately $816 per metric tonne or $0.82 per KG as of January 2022. The cost of air fuel can also depend on factors such as delivery fees and the cost of refueling aircraft.
Air Fuel Characteristics and Values Table
| Characteristics | Values |
|---|---|
| Definition | Air–fuel ratio (AFR) is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process. |
| Combustion | The combustion may take place in a controlled manner, such as in an internal combustion engine or industrial furnace, or may result in an explosion (e.g., a dust explosion). |
| Ignition | The air–fuel ratio determines whether a mixture is combustible. Typically, a range of air-to-fuel ratios exists, outside of which ignition will not occur. These are the lower and upper explosive limits. |
| Anti-pollution and Performance Tuning | The air–fuel ratio is an important measure for anti-pollution and performance tuning in internal combustion engines or industrial furnaces. |
| Stoichiometric Mixture | A stoichiometric mixture has just enough air to completely burn all the available fuel. The ratio is about 14.7:1 for gasoline fuel, i.e., 14.7 grams of air for every gram of fuel. |
| Lean Mixture | Ratios higher than stoichiometric, where air is in excess, are considered "lean." Lean mixtures are more efficient but may lead to higher temperatures and the formation of nitrogen oxides. |
| Rich Mixture | Mixtures with less than a 14.7:1 ratio are considered rich mixtures, used for acceleration and high-load conditions to produce cooler combustion products and prevent cylinder head overheating. |
| Jet Fuel Price (Global Average) | The global average jet fuel price can vary; for example, in June 2025, it was $91.82/bbl, a 1.2% decrease from the previous week. |
| Jet Fuel Price (US National Average) | The national average price for jet fuel in the US is $6.29 per gallon, while the national average price for Sustainable Aviation Fuel (SAF) is $8.72 per gallon. |
| Jet Fuel Price (Europe) | There is currently no tax on aviation fuel in Europe. As of January 2022, the price of Jet A1 fuel was approximately $816 per metric tonne, or about $0.82 per KG. |
| Fuel Efficiency (Airbus A380) | The Airbus A380, a jumbo jet, burns about 4,600 gallons (11,400 liters) of fuel per hour and can carry over 800 passengers, offering a 20% increase in per-passenger fuel efficiency over the Boeing 747. |
| Fuel Efficiency (Boeing 747) | A Boeing 747 uses about 1 gallon (4 liters) of fuel per second or 36,000 gallons (150,000 liters) over a 10-hour flight. It burns approximately 5 gallons of fuel per mile (12 liters per kilometer). |
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What You'll Learn
Jet fuel prices vary daily and by region
Jet fuel prices vary daily and are influenced by various factors such as demand, market holidays, and specific regions. According to GlobalAir.com, the national average price for jet fuel in the United States as of August 6, 2025, was $6.29 per gallon, with prices varying across different FAA regions. The FAA Alaska region reported the highest jet fuel price at $8.09, while the FAA Central region had the lowest price at $5.61.
These price variations are also observed in different cities within the US. For instance, Argus Media provides daily jet fuel spot prices for Chicago, Houston, Los Angeles, and New York, recognizing the dynamic nature of fuel pricing.
The fluctuations in jet fuel prices are not limited to the US; they occur globally. The Jet Fuel Price Monitor by IATA provides weekly updates on jet fuel prices, reflecting the average prices paid at refineries worldwide. For instance, the global average jet fuel price for one week in 2025 was $91.82 per barrel, a 1.2% decrease from the previous week.
These price changes are assessed daily by organizations like Platts, which publishes the Platts Jet Fuel Price Index. This index reflects the spot prices in relevant regional centers, taking into account market holidays and demand variations. The individual Platts assessments are weighted based on regional demand and compared with average spot prices in 2000 to generate a percentage reflecting the overall price change over time. For example, an index value of 200 indicates a doubling of the price since the year 2000.
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Air-fuel ratio (AFR) determines combustion
The air-fuel ratio (AFR) is a critical parameter in combustion engines as it determines the efficiency and performance of the engine. The AFR is the ratio of the mass of air to the mass of fuel present in a combustion process. This process can take place in a controlled manner, such as in an internal combustion engine, or it may result in an explosion, like a dust explosion.
The combustion of fuel requires a minimum stoichiometric ratio of air to fuel, which is the chemically correct ratio that allows for complete combustion without any excess air or fuel. For example, for gasoline engines, the stoichiometric ratio is approximately 14.7:1 (14.7 parts of air to 1 part of fuel by mass). The stoichiometric ratio is important because it ensures that there is enough air to completely burn all of the fuel. This ratio is also known as the stoichiometric mixture or "stoich".
The AFR is important for anti-pollution and performance-tuning reasons. If the ratio deviates too far from the stoichiometric ratio, ignition may not occur. These limits are known as the lower and upper explosive limits. The AFR also determines how much energy is released during combustion and how much unwanted pollutants are produced.
The AFR can be monitored using an air-fuel ratio meter, also called an air-fuel ratio gauge. This device measures the amount of residual oxygen (for lean mixes) or unburned hydrocarbons (for rich mixtures) in the exhaust gas. By measuring the oxygen content in the exhaust gases, the meter can provide feedback to the Engine Control Module (ECM) to adjust the fuel injection for optimal combustion. This ensures the engine operates at the ideal AFR for optimal performance and emission control.
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$13.09 $13.79
Lean mixtures are more efficient but may cause higher temperatures
The price of airplane fuel varies depending on the type of fuel and the region. The national average price for jet fuel in the US is $6.29 per gallon, while the global average jet fuel price is $91.82 per barrel.
Now, onto the topic of lean mixtures:
Mixture leaning or enrichment, also known as regulation, is a technical skill that involves adjusting the ratio of fuel to air. A common misconception is that only reciprocating aircraft engines require mixture regulation, but in reality, both aircraft and automotive engines employ devices that effect automatic mixture ratio changes. Mixture regulation is essential for optimal engine operation and can provide benefits beyond just fuel economy.
When an engine runs lean, it has a higher air-to-fuel ratio, resulting in more oxygen in the mixture. This higher oxygen content can lead to an increase in combustion and exhaust temperatures. This is because lean mixtures cool the cylinder less effectively than richer mixtures, as there is less fuel to evaporate and absorb heat. The slower burning rate of lean mixtures also means that there is less time for the engine to extract mechanical energy during the power stroke, resulting in unextracted energy remaining as heat.
While lean mixtures can improve fuel economy, they may also have negative consequences. If the mixture is too lean, it can create an oxidizing atmosphere, damaging the exhaust valves. Additionally, the higher temperatures caused by lean mixtures can lead to engine seizures or cause a valve to burn. Therefore, it is crucial to carefully regulate the mixture to balance fuel efficiency and engine health.
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The price of jet fuel is aligned with the price of oil
The price of jet fuel is influenced by several factors, including the type of aircraft, engine technology, mission requirements, and market dynamics. Jet fuel, also known as Jet A1, is a kerosene-based fuel commonly used in commercial aviation. The price of jet fuel is closely aligned with the price of oil, which fluctuates daily.
As of January 2022, the price of Jet A1 was approximately $816 per metric tonne, or about $0.82 per KG. This price had doubled compared to January 2021, where the cost was around $430 per metric tonne. The COVID-19 pandemic significantly impacted oil prices, leading to a collapse in prices. In May 2020, Jet A1 prices dropped to as low as $200 per metric tonne, or $0.20 per KG.
The cost of jet fuel also varies based on geographical location and market demand. In the United States, "Jet A" fuel is commonly used, while "Jet A-1" is utilized in Europe, Asia, and other international markets. Jet fuel is traded in bulk, and supply issues or refinery disruptions can cause significant price fluctuations. For example, in early April 2022, jet fuel supplies were scarce, leading to trading at a premium and briefly pushing prices above $7 per gallon.
The price of jet fuel has a direct impact on the operational costs of airlines. Major airlines spend hundreds of millions of dollars on jet fuel each quarter. The cost of filling a single Boeing 747, a commonly used aircraft, can reach nearly $130,000. Additionally, the price of jet fuel does not usually include delivery fees or refueling charges, further increasing the overall cost for airlines.
The alignment between jet fuel and oil prices is essential for airlines' financial planning. Hedging is a strategy employed by airlines to mitigate risk and manage costs. By agreeing to a fixed price for a set period, airlines can protect themselves from price fluctuations. However, hedging can also result in financial losses if the airline stops flying during the agreed-upon period.
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The cost of aviation fuel is about $0.82 per KG
Aviation fuel, or jet fuel, is a refined petroleum product used to power aircraft. The price of jet fuel can vary depending on various factors such as demand, market conditions, and regional differences. As of the latest update, the global average jet fuel price is $91.82 per barrel (bbl). This price is not static and is updated weekly.
The Jet Fuel Price Index provides weekly updates on the jet fuel price, price index, and yearly price average. These prices are based on daily assessments of jet fuel spot prices in the physical spot market of relevant regional centers. When a market is not assessed on a particular day, the previous working day's spot market price assessment is used.
The price of jet fuel has an impact on the fuel bill of the global airline industry. The cost of aviation fuel is a significant expense for airlines, and fluctuations in fuel prices can affect their financial performance. As a result, airlines closely monitor fuel prices and may employ fuel hedging strategies to manage their fuel costs.
The provided cost of aviation fuel, approximately $0.82 per KG, may be a rough estimate or a conversion from a different unit of measurement. It is important to note that the cost of aviation fuel can vary across regions and airports, and it is influenced by various factors such as supply and demand dynamics, local taxes, and distribution costs. Additionally, the cost of jet fuel is just one component of an airline's overall operating expenses, which also include aircraft maintenance, crew salaries, airport fees, and more.
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Frequently asked questions
The price of jet fuel is variable and dependent on the price of oil, which fluctuates daily. As of January 2022, the price of Jet A1 was approximately $816 per metric tonne, or $0.82 per KG. This equates to roughly $0.20 per litre, or $0.53 per gallon.
A Boeing 747-400 burns approximately 5 gallons of fuel per mile (12 litres of fuel per kilometre). On a 10-hour flight, this equates to 36,000 gallons (150,000 litres).
A Jumbo Jet (Boeing 747-400) flying from London to New York burns approximately 70,000 kilograms of fuel, which equates to 82,300 litres. This would cost approximately £53,500 or $64,300.
