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MPG to L/100km Converter

Time & Speed

Convert fuel efficiency between MPG (US/UK), L/100km, and km/L instantly. Handles the non-linear reciprocal formula correctly. Free, in-browser, no data stored.

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What is a MPG↔L/100km?

The MPG to L/100km Converter converts fuel efficiency between the major measurement standards used around the world: Miles per Gallon (US and UK variants), Litres per 100 Kilometres, and Kilometres per Litre. The conversion is non-linear — MPG and L/100km are reciprocal to each other — which is why a simple multiplication factor does not work.

Fuel efficiency measurement differs by region: the US uses MPG (Miles Per Gallon, US gallons); the UK uses MPG (Imperial gallons, 20% larger than US gallons); continental Europe, India, Australia, and most other countries use L/100km; and India's ARAI ratings often publish km/L alongside L/100km.

The non-linear relationship: MPG and L/100km are reciprocals. Doubling a car's MPG halves its L/100km. This reciprocal nature means the practical fuel savings are not equal across the MPG range: improving from 10 MPG to 20 MPG saves far more fuel than improving from 40 MPG to 50 MPG.

Supported unit conversions:

  • MPG (US gallon) ↔ L/100km
  • MPG (UK/Imperial gallon) ↔ L/100km
  • km/L (Indian and international standard) ↔ L/100km
  • Miles per Litre ↔ L/100km
  • Any combination of the above via the L/100km intermediate

For the general fuel efficiency converter covering all units, see the Fuel Efficiency Converter. For individual component conversions, see the Miles to Kilometres Converter and Gallons to Litres Converter.

All calculations are client-side. No data is transmitted.

How to use this MPG↔L/100km calculator

  1. Select the FROM unit — MPG US, MPG UK, L/100km, km/L, or mi/L.
  2. Enter the value — type or use the controls for the fuel efficiency figure.
  3. Select the TO unit — the target measurement standard.
  4. Read the result — the converted value appears instantly.
  5. Use the swap button (⇅) to reverse the conversion direction.
  6. Reference table — view all unit equivalents simultaneously for the entered value.

Formula & Methodology

All conversions use L/100km as the canonical intermediate unit:

| From | To L/100km | From L/100km |
|---|---|---|
| MPG (US) | 235.214 ÷ MPG | 235.214 ÷ L100 |
| MPG (UK) | 282.481 ÷ MPG | 282.481 ÷ L100 |
| km/L | 100 ÷ km_l | 100 ÷ L100 |
| mi/L | 160.934 ÷ mi_l | 160.934 ÷ L100 |

Derivation of the US constant (235.214):
1 US gallon = 3.78541 litres (exact) 1 mile = 1.60934 km (exact) L/100km = (litres per gallon × 100) ÷ (km per mile × MPG)         = (3.78541 × 100) ÷ (1.60934 × MPG)         = 378.541 ÷ (1.60934 × MPG)         = 235.214 ÷ MPG

Worked example: 30 MPG (US)
L/100km = 235.214 ÷ 30 = 7.84 L/100km km/L = 100 ÷ 7.84 = 12.76 km/L MPG (UK) = 282.481 ÷ 7.84 = 36.03 MPG (UK)

Common reference values:

| MPG (US) | L/100km | km/L |
|---|---|---|
| 20 | 11.76 | 8.50 |
| 25 | 9.41 | 10.63 |
| 30 | 7.84 | 12.75 |
| 35 | 6.72 | 14.88 |
| 40 | 5.88 | 17.00 |
| 50 | 4.70 | 21.25 |

Frequently Asked Questions

MPG (Miles Per Gallon) is the US standard unit of fuel efficiency, measuring how many miles a vehicle can travel on one US gallon of fuel (3.785 litres). The US adopted MPG as its standard fuel economy metric under the Energy Policy and Conservation Act of 1975, when NHTSA began requiring fuel economy labels on new cars. Higher MPG means better fuel efficiency — a car with 40 MPG is more fuel-efficient than one with 25 MPG.
L/100km (Litres per 100 Kilometres) is the fuel efficiency metric used in most countries outside the US — including India, the EU, Australia, China, and Canada. It measures how many litres of fuel a vehicle consumes to travel 100 kilometres. Unlike MPG, lower L/100km means better efficiency: a car that uses 5 L/100km is more efficient than one using 8 L/100km.
The formula is: L/100km = 235.214 ÷ MPG (US). This derives from the exact values: 1 US gallon = 3.78541 litres and 1 mile = 1.60934 kilometres, giving L/100km = (3.78541 × 100) ÷ (1.60934 × MPG) = 235.214 ÷ MPG. Note that the relationship is reciprocal — you divide into a constant, not multiply — so doubling the MPG halves the L/100km.
The US gallon (3.785 litres) and the UK imperial gallon (4.546 litres) are different volumes. A car rated at 40 MPG (US) is actually less efficient than a car rated at 40 MPG (UK), because the UK gallon is 20% larger. The L/100km conversion constant for UK MPG is 282.481 (not 235.214). Always clarify which MPG standard is being used when comparing vehicles sold in different markets.
Indian passenger cars typically achieve between 4 and 7 L/100km under real-world driving conditions. Compact hatchbacks like the Maruti Suzuki Swift achieve around 4.5–5.5 L/100km; mid-size sedans around 6–7 L/100km; mid-size SUVs around 7–10 L/100km. The ARAI (Automotive Research Association of India) published fuel efficiency figures are test-cycle results — real-world figures are typically 15–25% higher (worse) than the ARAI figure.
km/L (Kilometres per Litre) is the Indian equivalent of MPG — it measures how far you can travel on one litre of fuel. A higher km/L is better, like a higher MPG. The conversion between km/L and L/100km is: L/100km = 100 ÷ km/L. For example, a car achieving 20 km/L uses 5 L/100km. ARAI efficiency ratings in India are often published in km/L.
No — all calculations run entirely in your browser. No values are sent to any server, stored, or logged. The tool works offline once loaded.
The conversion is non-linear because MPG and L/100km are reciprocals of each other — you divide a constant by one to get the other. When you plot MPG vs L/100km on a graph, the relationship is a curve (hyperbola), not a straight line. This means that improving from 10 MPG to 20 MPG saves much more fuel than improving from 40 MPG to 50 MPG, even though both are 10 MPG improvements.
Select the unit you are converting from (MPG US, MPG UK, L/100km, or km/L) in the FROM dropdown, enter the value, and select the target unit in the TO dropdown. The converted value appears instantly. You can also swap the units using the swap button to reverse the conversion.
For the US market, a car achieving over 30 MPG (city/highway combined) is considered fuel-efficient for a conventional petrol engine. The US EPA fuel economy standards (CAFE) target a fleet average of about 40 MPG by 2026. Hybrid vehicles typically achieve 45–55 MPG; plug-in hybrids 50–70 MPGe (miles per gallon equivalent); and fully electric vehicles are rated in MPGe (100+ MPGe for most EVs). In L/100km terms: 30 MPG US ≈ 7.8 L/100km.
Also known as
MPG to L/100kmfuel efficiency convertermiles per gallon to litresL/100km to MPGkm per litre convertercar fuel consumption convertermpg calculatorlitres per 100 km converterfuel economy calculator