3. Conversion Table

Trip, Range, Annual Cost, and Comparison

Fuel Consumption Converter Formulas

Fuel economy and fuel consumption describe the same driving efficiency from opposite directions. Fuel economy measures distance per unit of fuel, so a higher number is better. Fuel consumption measures fuel used per unit of distance, so a lower number is better. The most common fuel economy unit in the United States is miles per US gallon. The most common consumption unit in many metric countries is litres per 100 kilometres.

Imperial gallon calculations use a larger gallon:

Kilometres per litre converts directly into litres per 100 kilometres:

Electric vehicle consumption is often measured as kWh per 100 kilometres or kWh per 100 miles:

Trip fuel cost uses total distance, efficiency, and fuel price:

EV trip charging cost is:

Range from tank or battery size:

Complete Guide to Fuel Consumption Conversion

Fuel consumption conversion is useful because drivers, manufacturers, governments, and countries do not all use the same efficiency units. A car may be advertised as 30 mpg in the United States, 36 mpg in the United Kingdom, 7.8 L/100 km in Europe, or 12.8 km/L in another market. These numbers can describe the same vehicle, but they look very different until the units are converted correctly.

The key difference is that some units measure distance per fuel and others measure fuel per distance. Miles per gallon, kilometres per litre, miles per litre, and kilometres per gallon are distance-per-fuel units. For those units, a higher number means better efficiency. Litres per 100 kilometres, gallons per 100 miles, and kWh per 100 kilometres are consumption units. For those units, a lower number means better efficiency.

This difference creates a common misunderstanding called the MPG illusion. Improving from 10 mpg to 15 mpg saves more fuel over the same distance than improving from 30 mpg to 35 mpg, even though both improvements are 5 mpg. Consumption units such as L/100 km make this clearer because they show fuel used directly. A 10 mpg vehicle uses much more fuel per mile than a 30 mpg vehicle, so small changes at low efficiency can produce large savings.

A fuel consumption converter helps compare vehicles across countries. The United States commonly uses mpg US, which is based on the US liquid gallon. The United Kingdom historically uses mpg imperial, which is based on the larger imperial gallon. Because the imperial gallon is larger, the same vehicle will show a higher mpg number in imperial mpg than in US mpg. This does not mean the vehicle changed; only the gallon definition changed.

Litres per 100 kilometres is a direct consumption unit. It answers the question: how many litres are needed to drive 100 kilometres? If a vehicle uses 5 L/100 km, it is more efficient than one using 9 L/100 km. This unit is intuitive for fuel-cost planning because you can multiply the fuel used by the price per litre. For example, a 500 km trip at 6 L/100 km uses 30 litres.

Kilometres per litre is the inverse style. It answers: how many kilometres can the vehicle travel on one litre? A vehicle that gets 20 km/L is more efficient than one that gets 10 km/L. The conversion to L/100 km is \(100/(\text{km/L})\). Therefore, 20 km/L equals 5 L/100 km, while 10 km/L equals 10 L/100 km.

Electric vehicles use energy instead of liquid fuel. The most common EV consumption units are kWh/100 km, kWh/100 miles, mi/kWh, km/kWh, and MPGe. A lower kWh/100 km means the EV uses less electricity to travel the same distance. A higher mi/kWh or km/kWh means the EV travels farther on each unit of electricity.

MPGe is a comparison unit used to compare electric and alternative-fuel vehicles with gasoline vehicles. The EPA equivalence is based on 33.7 kWh as the energy equivalent of one gallon of gasoline. A vehicle rated at 100 MPGe uses the energy equivalent of one gallon of gasoline to travel 100 miles. MPGe is useful for energy comparison, but it does not automatically mean the same operating cost because electricity prices and fuel prices vary.

Cost conversion is different from energy conversion. A gasoline vehicle and an EV can be compared by cost per distance. For gasoline, calculate gallons or litres used and multiply by the fuel price. For an EV, calculate kWh used and multiply by the electricity price. In many regions, EVs can cost less per mile, but the result depends on charging price, vehicle efficiency, driving speed, climate, and charging losses.

Fuel consumption also depends on real-world conditions. Official ratings are measured under defined test procedures, but drivers may see different results. Speed, traffic, tyre pressure, roof racks, air conditioning, cold weather, aggressive acceleration, hill climbs, heavy cargo, towing, and short trips can all increase consumption. The converter does not predict driving style; it converts the number you enter.

Range estimation uses tank or battery size. If a car has a 14 US gallon tank and achieves 30 mpg US, the ideal range is about 420 miles. Real range may be lower because drivers usually do not use every drop of fuel and because fuel economy changes with conditions. For EVs, range from battery size is also an estimate because usable battery capacity, reserve buffers, temperature, speed, and charging behavior affect real driving range.

Emissions estimates are approximate. Tailpipe CO₂ from gasoline and diesel can be estimated from fuel burned. Electric vehicles have no tailpipe CO₂, but electricity generation can create upstream emissions depending on the power mix. This calculator includes editable emissions factors so users can adjust assumptions for gasoline, diesel, or EV electricity.

Annual fuel cost is useful for ownership planning. A vehicle that looks slightly more efficient may save a large amount over several years if you drive many miles. The calculator multiplies annual distance by fuel or energy use per distance, then multiplies by the selected fuel or electricity price. This lets users compare current and target efficiency over a full year, not just a single trip.

This page is also useful for education. Students can see inverse relationships, unit conversion, ratios, percentages, cost modelling, emissions factors, and dimensional analysis. A simple car efficiency question can become a practical lesson in algebra and environmental arithmetic.

This calculator is not an official exam score calculator. There is no universal score guideline, score table, or next exam timetable for a fuel consumption converter. It can support physics, chemistry, environmental science, engineering, personal finance, and applied mathematics, but official exam schedules and grading rules must come from the relevant school, board, or course provider.

Reference Links

Useful references: EPA vehicle CO₂ factors, EPA fuel economy and EV range testing, FuelEconomy.gov, and NIST metric and measurement resources.

How to Use the Fuel Consumption Converter

1. Enter a fuel economy or consumption value. Use MPG, L/100 km, km/L, kWh/100 km, MPGe, or another supported unit.
2. Select the input unit. The tool identifies whether the value is liquid fuel or EV electricity.
3. Set trip details. Enter distance, distance unit, trip type, and fuel or electricity price.
4. Add tank or battery size. The calculator estimates driving range.
5. Review annual cost. Enter annual distance to estimate yearly fuel or charging cost.
6. Compare efficiency. Add a second efficiency value to estimate savings or extra cost.
7. Export results. Copy the result, download CSV, or print/save the report.

Fuel Consumption Converter FAQ