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Fuel Economy Converter

Convert MPG, L/100km, and km/L instantly. Includes a trip cost estimator and vehicle efficiency rating scale for international drivers and fleet managers.

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Category Car Calculators

Trip Cost Estimator (Optional)

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About

Fuel consumption metrics vary significantly across borders. The US and UK both use MPG, yet the Imperial gallon differs from the US gallon by approximately 20%. Meanwhile, most of the world utilizes L/100km, an inverse metric where lower numbers indicate better efficiency. Misinterpreting these values leads to inaccurate logistical budgeting and range anxiety.

This tool normalizes these disparate standards. It converts between volume-based (MPG) and distance-based (L/100km) metrics using precise conversion factors. The integrated Trip Cost Calculator determines the financial impact of a specific efficiency rating over a set distance, factoring in current fuel prices. This is critical for cross-border travel planning and comparing vehicle operating costs.

fuel efficiency mpg converter gas mileage trip cost calculator liters per 100km

Formulas

The relationship between US MPG and L/100km is inverse. The formula uses the constant C derived from the conversion of miles to kilometers and gallons to liters.

L/100km = 235.215MPGUS

For trip cost calculation, the formula integrates distance and price:

Cost = Distancekm100 × EfficiencyL/100km × Priceper L

Reference Data

MetricUnit DefinitionConversion Factor (to US MPG)Typical Range (Sedan)
US MPGMiles per US Gallon1.025 - 35
UK MPGMiles per Imperial Gallon≈ 0.832730 - 42
L/100kmLiters per 100 Kilometers235.215x6.7 - 9.4
km/LKilometers per Liter× 2.35210 - 15
MPGeMPG Equivalent (Electric)33.7 kWh = 1 gal90 - 130
L/10kmLiters per 10 Kilometers23.52x0.6 - 0.9
gal/100miGallons per 100 Miles100x2.8 - 4.0
Metric Mile10 kmN/AN/A

Frequently Asked Questions

In MPG (Miles Per Gallon), a higher number is better because you travel further on fixed fuel. In L/100km, a lower number is better because you consume less fuel for a fixed distance. This inversion often confuses drivers switching between metric and imperial systems.
Yes. An Imperial Gallon is approximately 1.2 US Gallons. The tool applies a factor of 1.20095 when converting between UK MPG and US MPG to ensure accuracy for UK vehicle standards.
MPGe (Miles Per Gallon equivalent) represents the distance an EV can travel on 33.7 kWh of electricity, which contains the same energy potential as one gallon of gasoline.
Aerodynamic drag increases quadratically with speed. While this calculator uses your average efficiency input, driving consistently above 100 km/h (62 mph) typically reduces efficiency by 15-25%, increasing the actual trip cost.