Miles per Gallon Calculator
Calculate MPG (miles per gallon), convert to L/100km, estimate fuel costs, compare vehicle efficiency, and track CO2 emissions with our comprehensive fuel economy calculator.
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About Miles per Gallon Calculator
Welcome to the Miles per Gallon Calculator, a comprehensive fuel economy tool that helps you calculate MPG, estimate trip costs, compare vehicles, and track CO2 emissions. Whether you're monitoring your car's efficiency, planning a road trip budget, or comparing vehicles for a purchase decision, this calculator provides all the metrics you need.
How to Calculate Miles per Gallon (MPG)
Calculating your vehicle's fuel economy is simple with the MPG formula:
For example, if you drove 350 miles on 12.5 gallons of gas, your MPG would be: 350 ÷ 12.5 = 28 MPG.
Step-by-Step MPG Calculation
- Fill your tank completely at a gas station and record your odometer reading (or reset your trip meter)
- Drive normally until you need to refuel again (at least 100+ miles for accuracy)
- Fill up again and note how many gallons it took to refill
- Calculate the distance driven and divide by gallons used
What is a Good MPG?
Fuel economy varies significantly by vehicle type. Here's how different MPG ratings compare:
| MPG Range | Rating | Typical Vehicles |
|---|---|---|
| 50+ MPG | Excellent (A+) | Hybrids, EVs (MPGe), small efficient cars |
| 40-50 MPG | Very Good (A) | Compact cars, efficient sedans |
| 30-40 MPG | Good (B) | Mid-size sedans, small SUVs |
| 25-30 MPG | Average (C) | Crossovers, minivans |
| 20-25 MPG | Below Average (D) | Full-size SUVs, large sedans |
| <20 MPG | Poor (F) | Full-size trucks, performance vehicles |
Unit Conversions: MPG, L/100km, and km/L
Different countries use different fuel economy measurements. Our calculator automatically converts between all major units:
| Unit | Used In | Conversion |
|---|---|---|
| MPG (US) | United States | Base unit |
| MPG (UK) | United Kingdom | US MPG × 1.201 = UK MPG |
| L/100km | Europe, Australia, Canada | 235.21 ÷ MPG = L/100km |
| km/L | Japan, India, parts of Asia | MPG × 0.425 = km/L |
Note: Lower L/100km values mean better fuel economy (less fuel per distance), while higher MPG or km/L values indicate better efficiency.
CO2 Emissions and Fuel Consumption
Every gallon of gasoline burned produces approximately 8.89 kg (19.6 lbs) of CO2. Diesel produces about 10.18 kg (22.4 lbs) per gallon. The calculator estimates your carbon footprint based on fuel consumption and type.
CO2 Emissions by Fuel Type
| Fuel Type | CO2 per Gallon | CO2 per Liter |
|---|---|---|
| Regular Gasoline | 8.89 kg | 2.35 kg |
| Premium Gasoline | 8.89 kg | 2.35 kg |
| Diesel | 10.18 kg | 2.69 kg |
| E85 (Flex Fuel) | 5.76 kg | 1.52 kg |
How to Improve Your MPG
You can significantly improve your fuel economy with these driving habits and maintenance tips:
Driving Habits
- Drive smoothly - Avoid rapid acceleration and hard braking
- Maintain steady speed - Use cruise control on highways
- Reduce idling - Turn off engine if stopped for more than 60 seconds
- Slow down - Aerodynamic drag increases exponentially with speed
- Plan trips - Combine errands to reduce cold starts
Vehicle Maintenance
- Keep tires inflated - Under-inflated tires reduce MPG by up to 3%
- Regular tune-ups - A well-maintained engine runs more efficiently
- Use recommended oil - The right viscosity reduces friction
- Replace air filters - Clogged filters restrict airflow
- Reduce weight - Remove unnecessary cargo from your vehicle
US vs. UK Gallon: Understanding the Difference
There's an important distinction between US and UK (Imperial) gallons:
- US Gallon = 3.785 liters (128 fluid ounces)
- UK Gallon = 4.546 liters (160 fluid ounces)
This means UK MPG figures are approximately 20% higher than US MPG for the same vehicle. Our calculator supports both units for accurate international comparisons.
Frequently Asked Questions
How do I calculate miles per gallon (MPG)?
To calculate MPG, divide the total miles driven by the gallons of fuel used. For example, if you drove 350 miles on 12.5 gallons of gas, your MPG is 350 ÷ 12.5 = 28 MPG. Our calculator handles this automatically and also converts to km/L and L/100km.
What is a good MPG for a car?
A good MPG depends on vehicle type. For conventional cars: 40+ MPG is excellent, 30-40 MPG is good, 25-30 MPG is average. SUVs and trucks typically get 20-30 MPG. Hybrid vehicles can achieve 50+ MPG, while EVs have equivalent MPGe ratings of 100+.
How do I convert MPG to L/100km?
To convert MPG to L/100km (liters per 100 kilometers), divide 235.21 by the MPG value. For example, 30 MPG = 235.21 ÷ 30 = 7.84 L/100km. Lower L/100km values indicate better fuel efficiency.
How much CO2 does my car produce per mile?
A typical gasoline car produces about 8.89 kg of CO2 per gallon burned. If your car gets 25 MPG, it produces approximately 0.36 kg (0.79 lbs) of CO2 per mile. Diesel vehicles produce about 10.18 kg CO2 per gallon.
How much can I save by driving a more fuel-efficient car?
Fuel savings depend on your driving habits and fuel prices. At $3.50/gallon driving 15,000 miles/year: A car getting 30 MPG costs $1,750/year in fuel. A 20 MPG vehicle costs $2,625/year - that's $875 more annually. Use our comparison calculator for personalized estimates.
What's the difference between US and UK gallons?
A US gallon equals 3.785 liters while a UK (Imperial) gallon equals 4.546 liters - about 20% larger. This means UK MPG figures are higher than US MPG for the same vehicle. Our calculator supports both units.
Additional Resources
- FuelEconomy.gov - Official US Government Fuel Economy Information
- Fuel Economy in Automobiles - Wikipedia
Reference this content, page, or tool as:
"Miles per Gallon Calculator" at https://MiniWebtool.com/miles-per-gallon-calculator/ from MiniWebtool, https://MiniWebtool.com/
by miniwebtool team. Updated: Feb 01, 2026
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