Understanding Gas Mileage

Gas mileage, or fuel-efficiency, is a crucial factor when planning a trip or monitoring your vehicle’s performance. It represents the relationship between the distance traveled and the amount of fuel consumed. Various factors impact gas mileage, such as car model, production year, engine size, and driving habits.

Calculating Gas Mileage

You can determine gas mileage using the following formulas:

  • Imperial System: MPG=Average Gas Consumption (gallons)Distance (miles)​
  • Metric System: MPG=100kmDistance (km)×Average Gas Consumption (liters)​

However, a more straightforward method is to use the MPG calculator.

How to Use the MPG Calculator

  1. Input Distance: Specify the distance you plan to travel.
  2. Fuel Economy: Enter your car’s average fuel consumption.
  3. In the “Fuel Price and Trip Cost” section:
    • Price of Petrol: Input the current fuel price.

The calculator will then estimate the total fuel needed and the overall cost for your trip. If you’re sharing expenses, a gas estimator is available to split costs among participants.


1. How many gallons does my car hold?

  • Typically, cars have a fuel tank capacity of 12 to 16 gallons, depending on size.

2. How does a car calculate average mpg?

  • Modern cars use engine control to track fuel consumption and distance, calculating average mpg by dividing miles traveled by gallons consumed.

3. How do I calculate mpg?

  • Record miles traveled, find gallons used, and divide miles by gallons for your car’s mpg.

4. How much gas to drive 300 miles?

  • Assuming the average mpg is 25, you’d need 12 gallons (300 miles / 25 mpg).

5. What affects mpg?

  • Aggressive driving, cold weather, towing, air conditioning, and four-wheel-drive can impact mpg negatively.

This MPG calculator is a valuable tool for trip planning, saving both time and money. For unit conversions, a fuel economy converter is provided, supporting Miles per US gallon, Miles per UK gallon, and Liters per 100 km.