Mpg to L Per 100km Converter
Convert fuel economy between miles per gallon and liters per 100 kilometers. Enter values for instant results with step-by-step formulas.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Mpg to L Per 100km Converter
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Formula: L/100km = 235.215 / MPG (US)
Worked example — 32 MPG = 7.35 L/100km = 38.43 Imperial MPG | Annual cost: $1,687.50 for 15,000 miles
Formula
L/100km = 235.215 / MPG (US)
The conversion uses the constant 235.215, derived from (100 x 3.78541 liters/gallon) / 1.60934 km/mile. For Imperial MPG, the constant is 282.481. MPG and L/100km have an inverse relationship: higher MPG means lower L/100km. To convert km/L to L/100km, divide 100 by the km/L value.
Worked Examples
Example 1: Sedan Fuel Economy Comparison
Problem:A car is rated at 32 MPG (US). Convert to L/100km and calculate annual fuel cost for 15,000 miles at $3.60/gallon.
Solution:L/100km = 235.215 / 32 = 7.35 L/100km Imperial MPG = 32 / 0.832674 = 38.43 MPG (UK) km/L = 100 / 7.35 = 13.60 km/L Annual gallons = 15,000 / 32 = 468.75 gallons Annual fuel cost = 468.75 x $3.60 = $1,687.50 Cost per mile = $3.60 / 32 = $0.1125/mile
Result:32 MPG = 7.35 L/100km = 38.43 Imperial MPG | Annual cost: $1,687.50 for 15,000 miles
Example 2: European Car Specification Conversion
Problem:A European car is rated at 5.2 L/100km. Convert to US MPG and Imperial MPG.
Solution:US MPG = 235.215 / 5.2 = 45.23 MPG Imperial MPG = 282.481 / 5.2 = 54.32 MPG (UK) km/L = 100 / 5.2 = 19.23 km/L Gallons per 100 miles = (5.2 x 1.60934) / 3.78541 = 2.21 gal/100mi At 12,000 mi/yr: 12,000 / 45.23 = 265.3 gallons/year
Result:5.2 L/100km = 45.23 US MPG = 54.32 Imperial MPG = 19.23 km/L
Frequently Asked Questions
How do I convert MPG to liters per 100 km?
To convert miles per gallon (US) to liters per 100 kilometers, divide 235.215 by the MPG value. For example, 30 MPG equals 235.215 divided by 30 = 7.84 L/100km. This formula works because one US gallon equals 3.78541 liters and one mile equals 1.60934 kilometers. The constant 235.215 is derived from (100 x 3.78541) / 1.60934. Note that MPG and L/100km have an inverse relationship: as MPG increases, L/100km decreases. A car rated at 40 MPG uses 5.88 L/100km, while a car at 20 MPG uses 11.76 L/100km. This inverse relationship means equal MPG improvements save more fuel at lower MPG values.
What is the difference between US MPG and Imperial MPG?
US MPG and Imperial (UK) MPG differ because US gallons and Imperial gallons are different sizes. One US gallon equals 3.78541 liters, while one Imperial gallon equals 4.54609 liters, making the Imperial gallon about 20 percent larger. As a result, Imperial MPG figures are always higher than US MPG for the same vehicle. To convert US MPG to Imperial MPG, divide by 0.832674 (or multiply by 1.201). A car rated at 30 US MPG would be rated at approximately 36 Imperial MPG. This difference can cause significant confusion when comparing fuel economy figures between American and British automotive publications or when purchasing imported vehicles.
Why do some countries use L/100km instead of MPG?
Most countries outside the United States use liters per 100 kilometers because it is based on the metric system and provides a more intuitive understanding of fuel consumption. L/100km measures fuel consumed per distance rather than distance traveled per fuel unit, making it easier to calculate trip fuel costs: simply multiply L/100km by the distance in hundreds of kilometers and then by the fuel price. L/100km also has a linear relationship with fuel consumption, meaning going from 10 to 8 L/100km saves the same amount of fuel as going from 6 to 4 L/100km. In contrast, MPG has a nonlinear relationship where improving from 15 to 20 MPG saves more fuel than improving from 35 to 40 MPG.
What is considered good fuel economy in both MPG and L/100km?
Good fuel economy standards vary by vehicle type and region. For compact cars, 30 to 40 MPG (7.8 to 5.9 L/100km) is considered good, while hybrids achieve 40 to 60 MPG (5.9 to 3.9 L/100km). Midsize sedans averaging 25 to 30 MPG (9.4 to 7.8 L/100km) are acceptable. SUVs and trucks at 20 to 25 MPG (11.8 to 9.4 L/100km) are considered efficient for their class. Electric vehicles expressed in MPGe (miles per gallon equivalent) often exceed 100 MPGe. The US fleet average fuel economy standard (CAFE) requires approximately 49 MPG for passenger cars by 2026. European standards target approximately 4.1 L/100km (57.4 MPG) for new passenger cars.
Why does the MPG to L/100km conversion have a nonlinear relationship?
The relationship between MPG and L/100km is nonlinear because they are reciprocals of each other (one measures distance per fuel, the other fuel per distance). This creates what economists call the MPG illusion: at low MPG values, small improvements save much more fuel than equal improvements at high MPG values. Improving from 10 to 11 MPG saves about 91 gallons per 10,000 miles, while improving from 30 to 31 MPG saves only about 11 gallons. L/100km avoids this illusion because it is linear with fuel consumption. A reduction from 15 to 14 L/100km saves exactly the same amount of fuel per kilometer as a reduction from 7 to 6 L/100km.
How does driving behavior affect fuel economy?
Driving behavior can affect fuel economy by 20 to 40 percent under identical vehicle conditions. Aggressive acceleration and braking reduces fuel economy by 15 to 33 percent on highways and 10 to 40 percent in stop-and-go traffic. Speeds above 50 mph progressively reduce efficiency, with each 5 mph above 50 costing roughly an additional 0.24 dollars per gallon at average fuel prices. Excessive idling wastes 0.25 to 0.50 gallons per hour depending on engine size. Using cruise control on highways improves economy by 7 to 14 percent. Proper tire inflation alone can improve MPG by up to 3 percent, as underinflated tires increase rolling resistance and fuel consumption.
How do I calculate annual fuel cost from MPG?
To calculate annual fuel cost, divide your annual driving distance by your vehicle MPG to get gallons consumed, then multiply by the fuel price per gallon. For a car getting 25 MPG driven 12,000 miles per year at 3.50 dollars per gallon: 12,000 divided by 25 equals 480 gallons, times 3.50 equals 1,680 dollars per year. For L/100km, multiply L/100km by total kilometers driven divided by 100, then multiply by price per liter. Knowing your annual fuel cost helps evaluate whether upgrading to a more efficient vehicle makes financial sense. The difference between a 20 MPG and 30 MPG vehicle driving 12,000 miles at 3.50 per gallon is 600 dollars per year.
What is km/L and how does it compare to L/100km and MPG?
Kilometers per liter (km/L) measures how far a vehicle travels on one liter of fuel and is used in several Asian and South American countries including Japan, India, and Brazil. To convert km/L to L/100km, divide 100 by the km/L value. To convert km/L to US MPG, multiply by 2.35215. For example, 15 km/L equals 6.67 L/100km and 35.28 US MPG. Like MPG, km/L has the disadvantage of being nonlinear with fuel consumption, making it harder to directly compare savings between different efficiency levels. However, km/L remains popular because it uses metric units while still expressing efficiency as distance per fuel, which many consumers find intuitive.
How does temperature affect fuel economy?
Temperature significantly impacts fuel economy in multiple ways. In cold weather (around 20 degrees Fahrenheit), fuel economy drops 15 to 24 percent for short trips compared to 77 degrees Fahrenheit conditions. Cold engines are less efficient, motor oil thickens and increases friction, tire pressure drops (reducing efficiency by 0.2 percent per PSI lost), and winter gasoline blends contain less energy per gallon. Air conditioning in hot weather can reduce fuel economy by 5 to 25 percent depending on the system and driving conditions. At highway speeds, using air conditioning is actually more efficient than opening windows, which increases aerodynamic drag. The optimal temperature range for fuel economy is between 65 and 85 degrees Fahrenheit.
What is MPGe and how does it apply to electric vehicles?
MPGe (Miles Per Gallon equivalent) is a metric developed by the EPA to compare the energy efficiency of alternative fuel vehicles, including electric vehicles, to conventional gasoline vehicles. One gallon of gasoline contains 33.7 kWh of energy, so MPGe calculates how far an EV can travel on 33.7 kWh. A Tesla Model 3 rated at 132 MPGe means it travels 132 miles on 33.7 kWh of electricity, equivalent to using 25.5 kWh per 100 miles. In metric terms, this equals approximately 1.6 L/100km gasoline equivalent. While MPGe allows efficiency comparisons across fuel types, actual operating costs depend on local electricity versus gasoline prices. At average US rates, EVs cost roughly one-third to one-fifth as much per mile as gasoline vehicles.
References
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
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