Fuel Efficiency Converter
Convert units with the Fuel Efficiency Converter — enter a value and get accurate converted results instantly using verified formulas.
Formula
L/100km = 235.215 / MPG(US) | MPG(UK) = MPG(US) x 1.20095
Conversion uses the gallon-to-liter ratios: 1 US gallon = 3.78541 L, 1 Imperial gallon = 4.54609 L, 1 mile = 1.60934 km. Fuel cost = (Distance / Efficiency) x Price. CO2 = Liters consumed x 2.31 kg/L.
Worked Examples
Example 1: Convert 30 MPG (US) to Other Units
Problem: A car is rated at 30 MPG (US). Convert to L/100km, km/L, and MPG (UK). Calculate fuel cost for a 500-mile trip at $3.50/gallon.
Solution: L/100km = 235.215 / 30 = 7.84 L/100km\nkm/L = 100 / 7.84 = 12.76 km/L\nMPG (UK) = 282.481 / 7.84 = 36.03 MPG (UK)\nFuel for 500 miles = 500 / 30 = 16.67 gallons\nCost = 16.67 x $3.50 = $58.33\nCO2 = 16.67 x 3.785 x 2.31 = 145.8 kg
Result: 7.84 L/100km | 12.76 km/L | 36.03 MPG UK | $58.33 fuel cost
Example 2: European Car L/100km to US MPG
Problem: A European car is rated at 5.5 L/100km. Convert to US MPG and calculate fuel cost for 1000 km at $1.60/liter.
Solution: MPG (US) = 235.215 / 5.5 = 42.77 MPG\nMPG (UK) = 282.481 / 5.5 = 51.36 MPG\nkm/L = 100 / 5.5 = 18.18 km/L\nFuel for 1000 km = (5.5 / 100) x 1000 = 55 liters\nCost = 55 x $1.60 = $88.00\nCO2 = 55 x 2.31 = 127.1 kg
Result: 42.77 MPG US | 51.36 MPG UK | 55 liters needed | $88.00 cost
Frequently Asked Questions
What factors affect a vehicle's real-world fuel efficiency?
Real-world fuel efficiency can differ significantly from manufacturer ratings due to numerous factors. Driving behavior is the largest variable, with aggressive acceleration and hard braking potentially reducing efficiency by 15 to 33 percent compared to smooth driving. Speed matters enormously as aerodynamic drag increases with the square of velocity, meaning highway driving above 65 mph significantly hurts efficiency. Tire pressure being just 1 psi below recommended can reduce efficiency by 0.2 percent. Extra weight costs roughly 1 percent efficiency per 100 extra pounds. Air conditioning can reduce efficiency by 5 to 25 percent depending on conditions. Cold weather reduces efficiency by 15 to 24 percent for short trips as the engine and transmission need time to reach optimal operating temperature.
How do I calculate fuel cost for a road trip?
To calculate fuel cost for a road trip, you need three pieces of information: total distance, your vehicle's fuel efficiency, and the current fuel price. The formula is straightforward: Fuel Cost = (Distance / Fuel Efficiency) x Price per unit. For example, a 500-mile trip in a car getting 25 MPG with gas at $3.50 per gallon costs (500 / 25) x 3.50 = $70.00. In metric units, a 800 km trip at 8 L/100km with fuel at $1.50/liter costs (800 / 100) x 8 x 1.50 = $96.00. For more accuracy, account for city versus highway driving proportions, elevation changes, and weather conditions. Mountain driving and heavy headwinds can increase consumption by 10 to 20 percent above rated efficiency figures.
What is the CO2 emissions relationship to fuel consumption?
Carbon dioxide emissions are directly proportional to fuel consumed because CO2 is a fundamental combustion byproduct. Each liter of gasoline burned produces approximately 2.31 kilograms (5.09 pounds) of CO2, while each liter of diesel produces about 2.68 kilograms (5.91 pounds). Each US gallon of gasoline produces roughly 8.89 kg (19.6 lbs) of CO2. This means a car averaging 30 MPG emits about 296 grams of CO2 per mile, while a 20 MPG vehicle emits 444 grams per mile. Over 12,000 miles of annual driving, the 30 MPG car produces about 3.56 metric tons of CO2 versus 5.33 metric tons for the 20 MPG car. Understanding this direct relationship helps quantify the environmental impact of vehicle choice and driving habits.
Can I use Fuel Efficiency Converter on a mobile device?
Yes. All calculators on NovaCalculator are fully responsive and work on smartphones, tablets, and desktops. The layout adapts automatically to your screen size.
Is Fuel Efficiency Converter free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.