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MPG to L/100km Converter

Ready to calculate
Exact 235.2146 Constant.
US + UK + Metric.
Bidirectional.
100% Free.
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How it Works

01Pick Direction

MPG → L/100km or L/100km → MPG. Converts either way.

02Enter Value

Your car's fuel economy from EPA window sticker or trip computer.

03All Units

Outputs US MPG, UK MPG, L/100km, km/L, mi/L, km/gal.

04Rating

Categorizes as excellent, good, average, or poor based on class.

What is an MPG to L/100km Converter?

An MPG to L/100km converter — also called a fuel economy converter, MPG calculator, or L per 100km calculator — translates US miles-per-gallon fuel economy into European liters-per-100-kilometers (and back). These are not just different units for the same thing — they measure fuel economy in opposite directions. Higher MPG is better (more miles per fuel). Lower L/100km is better (less fuel per distance). Confusingly, the best number is highest in the US and lowest in Europe, which is why international car comparisons constantly need this tool.

The converter uses the exact mathematical constant 235.2146, derived from the precise definitions of 1 US gallon (3.78541 liters exactly) and 1 mile (1.609344 kilometers exactly). The formula is L/100km = 235.2146 / MPG(US), and it's symmetric: MPG(US) = 235.2146 / L/100km. This precision matters when reading EPA window stickers against international manufacturer specs — the rounding errors in casual conversions can misrepresent a vehicle's efficiency by 5-10%.

This tool outputs every common fuel-economy unit at once: US MPG (US gallon = 3.78541 L), UK/Imperial MPG (UK gallon = 4.54609 L — 20% larger, so UK MPG is 20% higher for the same efficiency), L/100km, km/L, miles/L, and km per US gallon. Conversions handle both directions — enter MPG to get L/100km, or enter L/100km to get MPG.

Also includes an efficiency rating that categorizes the result: excellent (60+ MPG, hybrids and EVs), very good (40-60 MPG, compact hybrids), good (30-40 MPG, sedans and small SUVs), average (20-30 MPG, midsize SUVs and pickups), below average (15-20 MPG, large SUVs and trucks), poor (under 15 MPG, V8 trucks and performance cars). Benchmarking against this scale contextualizes whatever specific value you're looking at.

Perfect for international car shoppers comparing US EPA MPG against Euro L/100km specs on the same model; travelers renting cars abroad translating rental agency fuel-efficiency claims to their home units; fleet managers benchmarking vehicles across regional spec sheets; automotive journalists writing for both US and international audiences; and engineering students doing fuel-consumption homework problems.

How It Works

Pick direction — MPG → L/100km or L/100km → MPG. Works both ways.
Enter value — MPG from EPA window sticker or L/100km from a European spec sheet.
Convert using exact constants: 1 US gal = 3.78541 L; 1 mile = 1.609344 km. L/100km = (100 × 3.78541) / (1.609344 × MPG) = 235.2146 / MPG.
Output all units: US MPG, UK/Imperial MPG (UK gal = 4.54609 L, 20% larger), L/100km, km/L, mi/L, km/gal.
Efficiency rating — classifies the result: excellent (60+ MPG), very good (40-60), good (30-40), average (20-30), below average (15-20), poor (under 15).

Conversion Formula

Constants:
  1 US gallon = 3.78541 liters
  1 Imperial (UK) gallon = 4.54609 liters
  1 mile = 1.609344 kilometers
Primary conversion:
  L/100km = 235.2146 / MPG(US)
  MPG(US) = 235.2146 / L/100km
  
UK to US MPG:
  MPG(UK) = MPG(US) × (4.54609 / 3.78541) = MPG(US) × 1.2009
km/L from L/100km:
  km/L = 100 / L/100km
Real-World Example

Worked Example

A 2024 Toyota Camry Hybrid rated 51 MPG combined by EPA:

  • L/100km = 235.2146 / 51 = 4.61 L/100km
  • km/L = 100 / 4.61 = 21.69 km/L
  • UK MPG = 51 × 1.2009 = 61.2 MPG (Imperial)
  • km/gal (US) = 21.69 × 3.78541 = 82.1 km/gal
  • Rating: Very Good (Compact / Hybrid)
  • Compare: a F-150 EcoBoost at 20 MPG = 11.76 L/100km (poor).

Who Uses This Converter?

1
International car shoppers comparing US-spec EPA MPG against Euro L/100km specs
2
Travelers renting cars abroad translating rental fuel efficiency to their home units
3
Fleet managers benchmarking vehicles across regional spec sheets
4
Automotive journalists writing for both US and international audiences
5
Engineering students doing fuel-consumption homework problems

Technical Reference

US EPA fuel economy — combined, city, highway ratings measured on the Federal Test Procedure (FTP-75 city cycle + Highway Fuel Economy Test). Window-sticker numbers include adjustments for real-world conditions.

EU WLTP — Worldwide Harmonised Light Vehicles Test Procedure. Replaced the older NEDC in 2017 for more realistic L/100km figures.

US vs UK gallon — US gallon is defined as 231 cubic inches = 3.78541 liters. UK Imperial gallon is 277.42 cubic inches = 4.54609 liters. Not interchangeable.

Key Takeaways

MPG and L/100km are mathematical inverses: higher MPG = lower L/100km = better efficiency. The magic constant 235.2146 comes from the derivation 100 × 3.78541 ÷ 1.609344 — memorize it and you can do the conversion in your head. UK Imperial MPG is 20% higher than US MPG for the same car because the UK gallon is 20% larger than the US gallon — always check which standard a publication is using (UK automotive magazines quote Imperial MPG, US magazines quote US MPG, and they look like very different numbers for the same car). A "40 MPG" car is either 5.9 L/100km (US MPG) or 7.06 L/100km (UK MPG — 40 Imperial MPG). For electric vehicles, MPGe (miles per gallon equivalent) uses 33.7 kWh ≈ 1 gallon of gasoline — a separate calculation that doesn't convert directly to L/100km without assuming a gas-to-electric equivalence.

Frequently Asked Questions

How do you convert MPG to L/100km?
Divide 235.2146 by the MPG (US) value. 30 MPG = 235.2146 / 30 = 7.84 L/100km. Same formula works both directions — L/100km × MPG = 235.2146 always.
What is a good MPG?
Hybrids and efficient compacts: 40-60 MPG. Sedans and small SUVs: 25-35 MPG. Midsize SUVs/pickups: 20-25 MPG. Large trucks/V8s: 15-20 MPG. EPA combined 2024 US fleet average: 28 MPG.
What is a good L/100km?
Under 5 L/100km is excellent (hybrids). 6-8 L/100km is typical compact/sedan. 10+ L/100km is SUV/truck territory. Diesel sedans often hit 4-5 L/100km on highway.
Why does the US use MPG?
Historical reasons and the imperial measurement system. Most of the world uses L/100km because it answers a different question: how much fuel do I need to travel a given distance, rather than how far can I go on a given amount of fuel.
Is UK MPG the same as US MPG?
No — UK uses the Imperial gallon (4.546 L), which is 20% larger than the US gallon (3.785 L). So UK MPG for the same car is 20% higher. A US-40-MPG car = ~48 MPG Imperial.
How do I convert L/100km to km/L?
km/L = 100 / (L/100km). An 8 L/100km car does 12.5 km per liter. L/100km is the inverse of km/L scaled to 100 km.
What is MPGe for electric cars?
MPG-equivalent — how many miles an EV travels on the energy content of 1 gallon of gasoline (33.7 kWh). A Tesla Model 3 at 138 MPGe uses 33.7 / 138 = 0.244 kWh/mile. Doesn't convert to L/100km without a gas-to-electric assumption.
How do I improve my MPG?
Gentle acceleration, steady highway cruising (55-65 mph optimal), proper tire pressure, remove excess weight, avoid roof racks when unused, skip premium if your car doesn't require it, use cruise control on flat highway. Typical 10-15% improvement possible without hardware changes.
Does air conditioning lower MPG?
Yes, by 2-5 MPG in city driving. On highway (60+ mph), A/C is roughly equivalent to driving with windows open due to aerodynamic drag — so either is fine above highway speed.
How does hybrid MPG compare to gas?
Hybrids gain 30-60% MPG in city driving (regenerative braking and engine-off at stops). Highway MPG advantage is smaller (10-20%). A Prius at 54 MPG city vs a comparable non-hybrid at 30 MPG city — huge difference in stop-and-go traffic.

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Disclaimer

Educational reference. Real-world MPG varies with driving style, terrain, and conditions. EPA ratings are lab-test standards.