MPG to L/100km Converter

MPG to L/100km conversion is essential for comparing fuel efficiency between vehicles marketed in different countries. The US uses miles per gallon (MPG); most of the world uses liters per 100 kilometers (L/100km). These are inversely related — higher MPG means lower L/100km, and vice versa.

Conversion formulas: L/100km = 235.215 ÷ MPG MPG = 235.215 ÷ L/100km

The constant 235.215 is derived from:

• 1 US gallon = 3.78541 liters
• 1 mile = 1.60934 km
• 100 × 3.78541 ÷ 1.60934 = 235.215

Note on gallon types:

• US gallon = 3.785 liters
• UK (Imperial) gallon = 4.546 liters
• UK MPG to L/100km: 282.5 ÷ UK MPG (different constant)
• European fuel efficiency is always L/100km; UK cars may list both

City vs highway vs combined fuel economy:

• City MPG: stop-and-go traffic; lowest efficiency; tests typically yield 10–30% worse than highway
• Highway MPG: constant speed; highest efficiency
• Combined MPG: weighted average (55% city, 45% highway), the EPA-listed number

Fuel cost calculation: Annual Fuel Cost = (Annual Miles × Fuel Price per gallon) ÷ MPG Or in metric: Annual Fuel Cost = (Annual km ÷ 100) × L/100km × Fuel Price per liter

Reference: common vehicle fuel economies (2024 US EPA)

• Toyota Prius (hybrid): 57 MPG combined = 4.1 L/100km
• Honda Civic: 36 MPG combined = 6.5 L/100km
• Toyota Camry: 32 MPG combined = 7.4 L/100km
• Ford F-150 (V8): 18 MPG combined = 13.1 L/100km
• Dodge Charger (V8): 18 MPG combined = 13.1 L/100km
• Hummer EV: equivalent to 47 MPGe = 5.0 L/100km equivalent

Worked example: A European car is rated at 5.5 L/100km. US equivalent?

MPG = 235.215 ÷ 5.5 = 42.8 MPG

Annual fuel cost comparison (15,000 miles/year at $3.50/gallon):

• 42.8 MPG: 15,000 ÷ 42.8 × $3.50 = $1,227/year
• 25 MPG (average US car): 15,000 ÷ 25 × $3.50 = $2,100/year Fuel savings: $873/year — substantial over 10 years of ownership.