Gas Mileage Calculator

Gas Mileage Calculator-Use our free Gas Mileage Calculator to calculate MPG, km/L, fuel consumption, trip fuel cost, and fuel economy. Convert between MPG, km/L and L/100 km with easy examples.Explore our complete collection of Engine Horsepower Calculator, Tire Size Calculator , Mileage Calculator,Dividend Calculator,Horsepower Calculator, conversion, and everyday calculators at CalculatorGuides.com to find the right tool for your needs.

Knowing how much fuel your vehicle uses can help you understand your driving costs and plan trips more accurately.

A Gas Mileage Calculator helps you calculate your vehicle’s fuel economy using the distance you travel and the amount of fuel you use.

You can use it to calculate:

• Miles per gallon (MPG)
• Kilometres per litre (km/L)
• Litres per 100 kilometres (L/100 km)
• Fuel consumed
• Fuel cost
• Trip fuel cost
• Distance possible with a full tank
• Cost per kilometre
• Cost per mile
• Estimated fuel needed for a trip

Whether you drive a car, SUV, pickup truck, motorcycle, or another petrol-powered vehicle, a mileage calculator can make fuel costs easier to understand.

Note: Your actual mileage can change because of traffic, speed, tyre pressure, vehicle load, weather, road conditions, driving style, air-conditioning use, and vehicle maintenance.

What Is a Gas Mileage Calculator?

A Gas Mileage Calculator is a tool that measures how efficiently a vehicle uses fuel.

The basic idea is simple:

Fuel Economy = Distance Travelled ÷ Fuel Used

For example, if a car travels:

500 kilometres

using:

40 litres of petrol

its fuel economy is:

500 ÷ 40 = 12.5 km/L

That means the vehicle travels approximately 12.5 kilometres on one litre of fuel.

What Is Gas Mileage?

Gas mileage describes how far a vehicle can travel using a certain amount of fuel.

In the United States, it is commonly expressed as:

MPG – Miles Per Gallon

In India and many other countries, vehicle mileage is commonly expressed as:

km/L – kilometres per litre

Another widely used measurement is:

L/100 km – litres per 100 kilometres

The three measurements describe the same basic idea but use different units.

Gas Mileage Formula

The basic formula is:

Mileage = Distance ÷ Fuel Used

For example:

Distance:

600 km

Fuel:

50 litres

Mileage:

600 ÷ 50 = 12 km/L

So the vehicle’s fuel economy is:

12 km/L

MPG Formula

For US measurements:

MPG = Miles Driven ÷ Gallons Used

For example:

Miles driven:

300 miles

Fuel used:

10 gallons

MPG:

300 ÷ 10 = 30 MPG

The vehicle travels approximately 30 miles for every gallon of fuel.

km/L Formula

For metric measurements:

km/L = Kilometres Driven ÷ Litres Used

Example:

Distance:

450 km

Fuel:

30 litres

Mileage:

450 ÷ 30 = 15 km/L

L/100 km Formula

L/100 km works differently from MPG and km/L because a lower number means better fuel efficiency.

Formula:

L/100 km = Litres Used ÷ Kilometres Driven × 100

Example:

Fuel used:

40 litres

Distance:

500 km

L/100 km:

40 ÷ 500 × 100 = 8 L/100 km

So the vehicle consumes approximately 8 litres of fuel per 100 kilometres.

MPG vs km/L vs L/100 km

Measurement	Meaning	Higher Number
MPG	Miles per gallon	Generally better
km/L	Kilometres per litre	Generally better
L/100 km	Litres used per 100 km	Lower is better

This difference is important when comparing vehicle specifications.

A car with 20 km/L is more fuel-efficient than one with 12 km/L.

But a car using 6 L/100 km is more efficient than one using 10 L/100 km.

US MPG vs UK MPG

There are two common gallon measurements:

• US gallon
• Imperial gallon

Therefore, US MPG and UK MPG are not the same.

One US gallon is approximately:

3.785 litres

One Imperial gallon is approximately:

4.546 litres

This means the same vehicle can have a different MPG number depending on which gallon is being used.

Always check whether a fuel-economy figure uses US MPG or Imperial MPG.

Convert MPG to km/L

For US MPG:

km/L = MPG × 0.425144

Example:

30 US MPG:

30 × 0.425144

≈ 12.75 km/L

So 30 US MPG is approximately 12.75 km/L.

Convert km/L to US MPG

Formula:

US MPG = km/L × 2.35215

Example:

15 km/L:

15 × 2.35215

≈ 35.28 US MPG

Convert MPG to L/100 km

For US MPG:

L/100 km = 235.215 ÷ MPG

Example:

30 US MPG:

235.215 ÷ 30

≈ 7.84 L/100 km

Convert L/100 km to MPG

For US MPG:

US MPG = 235.215 ÷ L/100 km

Example:

8 L/100 km:

235.215 ÷ 8

≈ 29.40 MPG

Convert km/L to L/100 km

Formula:

L/100 km = 100 ÷ km/L

Example:

20 km/L:

100 ÷ 20

= 5 L/100 km

So a vehicle delivering 20 km/L uses approximately 5 litres of fuel per 100 km.

Convert L/100 km to km/L

Formula:

km/L = 100 ÷ L/100 km

Example:

6 L/100 km:

100 ÷ 6

≈ 16.67 km/L

Gas Mileage Example

Suppose you drive:

800 km

and use:

50 litres

Fuel economy:

800 ÷ 50

= 16 km/L

The same result in L/100 km is:

100 ÷ 16

= 6.25 L/100 km

This means the vehicle uses approximately 6.25 litres for every 100 km.

How to Calculate Your Real Mileage

The most reliable way to calculate your real-world mileage is to use the full-tank method.

Step 1: Fill the Tank

Fill your fuel tank to the same practical level.

Step 2: Reset the Trip Meter

Record the trip-meter reading.

Step 3: Drive Normally

Drive your usual routes.

Step 4: Fill the Tank Again

At the next refill, record how many litres were added.

Step 5: Record the Distance

Use the distance shown on the trip meter.

Step 6: Calculate

Mileage = Distance ÷ Fuel Added

Example:

Distance:

600 km

Fuel added:

40 litres

Mileage:

15 km/L

This method gives you a useful real-world estimate.

Gas Mileage Calculator for a Road Trip

Suppose you are planning a:

1,200 km trip

Your vehicle gives:

15 km/L

Estimated fuel required:

1,200 ÷ 15

= 80 litres

If petrol costs:

₹100 per litre

Estimated fuel cost:

80 × ₹100

= ₹8,000

This does not include tolls, parking, maintenance, food, or other travel expenses.

Fuel Cost Formula

To calculate fuel cost:

Fuel Cost = Fuel Used × Price Per Litre

First calculate fuel required:

Fuel Required = Distance ÷ Mileage

Then:

Trip Fuel Cost = Distance ÷ Mileage × Fuel Price

Fuel Cost Example

Suppose:

Distance:

500 km

Mileage:

15 km/L

Fuel price:

₹100/L

Fuel required:

500 ÷ 15

≈ 33.33 litres

Fuel cost:

33.33 × ₹100

≈ ₹3,333

Cost Per Kilometre

Formula:

Cost per km = Fuel Price per Litre ÷ km/L

Example:

Fuel price:

₹100/L

Mileage:

15 km/L

Cost per km:

₹100 ÷ 15

≈ ₹6.67/km

Cost Per 100 Kilometres

Formula:

Cost per 100 km = L/100 km × Fuel Price

Example:

Fuel consumption:

8 L/100 km

Fuel price:

₹100/L

Cost:

8 × ₹100

= ₹800 per 100 km

Fuel Needed for a Trip

Formula:

Fuel Needed = Distance ÷ Mileage

Example:

Trip distance:

900 km

Mileage:

18 km/L

Fuel needed:

900 ÷ 18

= 50 litres

If the vehicle has a 45-litre fuel tank, you would need to plan at least one additional refuelling stop, depending on actual conditions and available fuel range.

Driving Range

Driving range is the approximate distance a vehicle can travel using the available fuel.

Formula:

Range = Fuel Tank Capacity × Mileage

Example:

Fuel tank:

50 litres

Mileage:

15 km/L

Estimated range:

50 × 15

= 750 km

Actual range can be lower because drivers generally do not use every last litre of fuel.

Gas Mileage Calculator for Petrol

For petrol vehicles:

Mileage = Distance ÷ Petrol Used

Example:

Distance:

500 km

Petrol:

35 litres

Mileage:

14.29 km/L

You can then use the petrol price to calculate the approximate trip cost.

Gas Mileage Calculator for Diesel

The same basic calculation works for diesel vehicles:

Mileage = Distance ÷ Diesel Used

Example:

Distance:

700 km

Diesel:

40 litres

Mileage:

17.5 km/L

The difference is that diesel prices and vehicle characteristics can differ from petrol vehicles.

Gas Mileage Calculator for CNG

CNG vehicles can use different units depending on how consumption is recorded.

If your fuel data is available in kilograms, use:

Distance ÷ CNG Used in kg

For example:

Distance:

300 km

CNG:

20 kg

Efficiency:

15 km/kg

The calculator should use the appropriate unit rather than treating kilograms as litres.

Hybrid Vehicle Fuel Economy

Hybrid vehicles can use fuel more efficiently, especially in certain urban driving conditions.

Actual efficiency depends on:

• Hybrid system
• Battery charge
• Driving conditions
• Traffic
• Speed
• Temperature
• Driving style

Use real fuel consumption over several refills for a more meaningful comparison.

EV vs Gas Mileage

Electric vehicles do not use petrol or diesel, so traditional MPG or km/L is not the best measurement.

EV efficiency is often expressed as:

• kWh/100 km
• km/kWh
• miles/kWh

For EV running-cost comparisons, you can calculate:

Electricity Cost = Electricity Used × Electricity Price

This can then be compared with petrol or diesel fuel costs.

City Mileage vs Highway Mileage

A vehicle often gets different fuel economy in city and highway driving.

City Driving

Fuel consumption can increase because of:

• Traffic
• Frequent stops
• Idling
• Acceleration
• Short trips

Highway Driving

Fuel economy can improve because of:

• More consistent speed
• Fewer stops
• Less idling

However, very high speeds can also reduce fuel efficiency.

Why Your Mileage Changes

Real-world fuel economy can vary because of:

• Driving style
• Traffic
• Speed
• Tyre pressure
• Vehicle load
• Road conditions
• Weather
• Air conditioning
• Engine condition
• Fuel quality
• Vehicle age
• Maintenance

Therefore, one tank of fuel may not represent your vehicle’s normal average.

Does Speed Affect Mileage?

Yes.

Driving at higher speeds can increase aerodynamic drag and fuel consumption.

Rapid acceleration and frequent braking can also reduce efficiency.

Smooth acceleration and maintaining a suitable steady speed can help improve fuel economy.

Does Tyre Pressure Affect Mileage?

Incorrect tyre pressure can affect rolling resistance and handling.

Under-inflated tyres can increase resistance and may reduce fuel efficiency.

Always follow the vehicle manufacturer’s recommended tyre-pressure specification rather than using a random pressure value.

Does Air Conditioning Affect Mileage?

Air conditioning can increase fuel consumption, particularly in some driving conditions.

The effect depends on:

• Vehicle
• Outside temperature
• AC system
• Driving speed
• Driving conditions

In hot weather, the effect can be more noticeable.

Does Vehicle Load Affect Mileage?

Yes.

Carrying additional weight means the engine has more work to do.

Removing unnecessary heavy items from the vehicle can help reduce fuel consumption.

How to Improve Gas Mileage

You can often improve fuel economy by:

• Maintaining correct tyre pressure
• Avoiding unnecessary idling
• Accelerating smoothly
• Avoiding excessive speed
• Removing unnecessary weight
• Maintaining the vehicle properly
• Planning routes
• Combining short trips
• Using cruise control where appropriate

Small improvements in fuel economy can add up over thousands of kilometres.

Gas Mileage and Fuel Price

Your vehicle’s mileage and the fuel price together determine the cost of driving.

For example:

Vehicle A:

20 km/L

Vehicle B:

12 km/L

At a fuel price of ₹100/L:

Vehicle A:

₹100 ÷ 20

= ₹5/km

Vehicle B:

₹100 ÷ 12

≈ ₹8.33/km

The difference becomes significant over a long distance.

Annual Fuel Cost

You can estimate annual fuel expenses using:

Annual Fuel Cost = Annual Distance ÷ Mileage × Fuel Price

Example:

Annual distance:

15,000 km

Mileage:

15 km/L

Fuel price:

₹100/L

Fuel required:

15,000 ÷ 15

= 1,000 litres

Annual fuel cost:

1,000 × ₹100

= ₹1,00,000

Fuel Cost Comparison

Suppose you drive:

20,000 km per year

Vehicle A

Mileage:

20 km/L

Fuel:

1,000 litres

At ₹100/L:

₹1,00,000

Vehicle B

Mileage:

12 km/L

Fuel:

1,666.67 litres

At ₹100/L:

approximately ₹1,66,667

Difference:

approximately ₹66,667 per year

This shows why fuel economy can have a meaningful effect on long-term vehicle costs.

Gas Mileage Calculator for Used Cars

If you are considering a used vehicle, do not rely only on the manufacturer’s mileage claim.

Ask about:

• Actual city mileage
• Highway mileage
• Fuel type
• Service history
• Tyre condition
• Engine condition
• Driving pattern

A test drive and several fuel records can provide a better real-world picture.

Manufacturer Mileage vs Real Mileage

Official fuel-economy figures are produced under specified testing conditions.

Real-world mileage can be different because your:

• Traffic
• Speed
• Route
• Weather
• Driving style
• Vehicle load

may not match the test conditions.

Therefore, treat official mileage as a reference rather than a guarantee.

Gas Mileage Calculator Formula Summary

Mileage in km/L

km/L = Kilometres Driven ÷ Litres Used

US MPG

MPG = Miles Driven ÷ US Gallons Used

L/100 km

L/100 km = Litres Used ÷ Kilometres Driven × 100

Fuel Needed

Fuel Needed = Distance ÷ Mileage

Fuel Cost

Fuel Cost = Fuel Needed × Fuel Price

Cost Per km

Cost/km = Fuel Price ÷ km/L

Driving Range

Range = Tank Capacity × Mileage

How to Use the Gas Mileage Calculator

Step 1: Enter Distance

Enter the distance travelled.

Step 2: Enter Fuel Used

Enter the amount of petrol, diesel, or other applicable fuel consumed.

Step 3: Select Units

Choose:

• Miles and gallons
• Kilometres and litres
• L/100 km

Step 4: Enter Fuel Price

If you want to calculate fuel cost, enter the current fuel price.

Step 5: Calculate

The calculator can show:

• Mileage
• MPG
• km/L
• L/100 km
• Fuel needed
• Fuel cost
• Cost per kilometre

Frequently Asked Questions

What is a Gas Mileage Calculator?

A Gas Mileage Calculator calculates how efficiently your vehicle uses fuel based on distance travelled and fuel consumed.

How do I calculate gas mileage?

Divide the distance travelled by the amount of fuel used.

For metric units:

km/L = kilometres ÷ litres

What is a good gas mileage?

There is no single number. It depends on the vehicle, engine, fuel type, size, weight, driving conditions, and purpose.

Is higher MPG better?

Yes. A higher MPG means the vehicle travels more miles using one gallon of fuel.

Is higher km/L better?

Yes. A higher km/L means the vehicle travels farther using one litre of fuel.

Is lower L/100 km better?

Yes. A lower L/100 km means the vehicle uses less fuel to travel 100 kilometres.

How do I convert km/L to MPG?

For US MPG:

US MPG = km/L × 2.35215

How do I convert MPG to km/L?

For US MPG:

km/L = MPG × 0.425144

What is the difference between US MPG and UK MPG?

US and Imperial gallons have different volumes, so MPG figures are not directly interchangeable.

How do I calculate fuel cost for a trip?

First calculate fuel required:

Distance ÷ Mileage

Then multiply the result by the fuel price.

How do I calculate cost per kilometre?

Divide the fuel price per litre by your km/L.

How do I calculate fuel needed for 1,000 km?

Divide 1,000 by your vehicle’s km/L.

For example, at 20 km/L:

1,000 ÷ 20

= 50 litres

How do I calculate my real-world mileage?

Use the full-tank method: record the distance between refuelling and divide it by the litres added at the next refill.

Does city driving reduce mileage?

It can. Traffic, idling, stopping, and frequent acceleration can increase fuel consumption.

Does highway driving improve mileage?

It often can, particularly at steady moderate speeds, but very high speeds can reduce fuel efficiency.

Does AC reduce mileage?

Air conditioning can increase fuel consumption, although the effect varies by vehicle and conditions.

Does tyre pressure affect mileage?

Yes. Incorrect tyre pressure can increase rolling resistance and affect fuel economy.

Can I use this calculator for diesel?

Yes. The same distance-and-fuel formula applies to diesel vehicles.

Can I use this calculator for CNG?

Yes, but use the correct CNG unit, such as kg, rather than treating CNG as litres.

Can I use this calculator for an electric car?

Traditional gas mileage measurements do not apply to EVs. EV efficiency is normally measured using electricity consumption such as kWh/100 km or km/kWh.

Is the Gas Mileage Calculator accurate?

The calculation is accurate for the information entered. Your actual future mileage can change because of driving conditions and vehicle factors.

Is the Gas Mileage Calculator free?

Yes. The CalculatorGuides.com Gas Mileage Calculator is free to use.

Gas Mileage Calculator – Important Things to Check

For the most useful result, record:

• Distance travelled
• Fuel used
• Fuel type
• Fuel price
• City/highway driving
• Vehicle load
• Tyre pressure
• Driving conditions

For real-world mileage, use several refuelling records and calculate the average instead of relying on a single trip.

Conclusion

A Gas Mileage Calculator makes it easy to understand your vehicle’s fuel efficiency and driving costs.

The basic calculation is:

Mileage = Distance ÷ Fuel Used

You can then convert the result into MPG, km/L, or L/100 km, depending on the measurement system you use.

The calculator can also estimate fuel needed for a trip, fuel cost, cost per kilometre, annual fuel expenses, and driving range. These calculations can help you compare vehicles and understand how changes in fuel prices or mileage affect your budget.

Remember that your actual mileage can change because of traffic, speed, tyre pressure, vehicle load, weather, air conditioning, maintenance, and driving style. For the most reliable personal result, use several full-tank measurements and calculate your average.

Use the CalculatorGuides.com Gas Mileage Calculator to quickly calculate fuel economy, trip fuel requirements, MPG, km/L, L/100 km, and estimated fuel costs.