Gas Mileage Calculator

Calculate your vehicle's fuel efficiency in MPG, km/L, and L/100km from the miles you drove and gallons you used.

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How to Calculate Gas Mileage (MPG)

Knowing your actual gas mileage is the foundation for understanding your vehicle's fuel costs. While the EPA provides estimated ratings, your real-world MPG depends on your specific driving habits, route conditions, and vehicle maintenance. This calculator takes your actual miles driven and gallons consumed to give you precise fuel efficiency numbers in multiple formats.

The calculation is simple but powerful: divide the total distance traveled by the fuel consumed. The result tells you exactly how efficiently your vehicle converts gasoline into miles of travel, which directly determines how much you spend on fuel.

Gas Mileage Formula

MPG = Miles Driven / Gallons Used
Cost per Mile = Price per Gallon / MPG
km/L = MPG x 0.4251
L/100km = 235.215 / MPG

For example, if you drove 350 miles on 12 gallons of gas at $3.50 per gallon, your MPG is 29.2, your cost per mile is $0.12, your fuel efficiency in metric units is 12.4 km/L or 8.1 L/100km, and your estimated annual fuel cost at 12,000 miles per year is $1,438.

How to Track Your MPG Accurately

  1. Fill your tank completely at a gas station. Let the pump auto-stop to ensure a full fill.
  2. Reset your trip odometer to zero, or write down your current mileage.
  3. Drive normally for a full tank of gas. Try to include your typical mix of city and highway driving.
  4. Fill up again completely at the same station if possible (pumps can vary). Record the gallons pumped.
  5. Calculate: Trip miles divided by gallons equals your MPG.
  6. Repeat 3-4 times and average the results for the most accurate reading.

Average MPG by Vehicle Type (2024)

  • Compact car -- 33-40 MPG (e.g., Honda Civic, Toyota Corolla)
  • Mid-size sedan -- 28-35 MPG (e.g., Toyota Camry, Honda Accord)
  • Small SUV/Crossover -- 26-33 MPG (e.g., Toyota RAV4, Honda CR-V)
  • Mid-size SUV -- 22-28 MPG (e.g., Ford Explorer, Chevrolet Traverse)
  • Full-size truck -- 18-24 MPG (e.g., Ford F-150, RAM 1500)
  • Hybrid sedan -- 45-58 MPG (e.g., Toyota Prius, Honda Insight)
  • Hybrid SUV -- 35-42 MPG (e.g., Toyota RAV4 Hybrid, Ford Escape Hybrid)
  • Sports car -- 20-28 MPG (e.g., Ford Mustang, Chevrolet Camaro)

10 Proven Ways to Improve Your MPG

Small changes in driving habits can yield significant fuel savings. Here are evidence-based techniques ranked by their impact on fuel efficiency:

  • Drive smoothly (up to 33% improvement) -- Avoid rapid acceleration and hard braking. Gradual speed changes are dramatically more fuel-efficient.
  • Observe the speed limit (7-14% improvement) -- Every 5 mph over 50 is like paying an additional $0.20-0.30 per gallon.
  • Remove excess weight (1-2% per 100 lbs) -- Clean out your trunk. An extra 100 pounds reduces MPG by about 1%.
  • Keep tires properly inflated (up to 3% improvement) -- Check tire pressure monthly. Under-inflated tires increase rolling resistance.
  • Use cruise control on highways (5-7% improvement) -- Maintaining constant speed prevents the fuel waste of speed variations.
  • Avoid excessive idling (saves fuel directly) -- Idling burns 0.25-0.50 gallons per hour. Turn off the engine if stopped for more than 30 seconds.
  • Use the recommended motor oil (1-2% improvement) -- The right viscosity reduces engine friction.
  • Replace air filters regularly (up to 10% improvement) -- A clogged air filter restricts airflow to the engine.
  • Plan and combine trips (saves total miles) -- Cold engines use more fuel. Combining errands into one trip is more efficient.
  • Remove roof racks when not in use (2-8% improvement) -- Roof-mounted cargo carriers significantly increase aerodynamic drag.

Understanding Fuel Economy Labels

The EPA fuel economy label on new cars shows three MPG numbers: city, highway, and combined. The combined rating is weighted 55% city and 45% highway to represent typical driving patterns. The label also shows an estimated annual fuel cost and a comparison to other vehicles in the same class. While useful for comparing vehicles, remember that your actual mileage will vary based on driving habits, conditions, and vehicle maintenance.

Since 2013, labels also include a fuel economy and greenhouse gas rating from 1-10, making it easier to compare vehicles across different classes and fuel types, including hybrids, plug-in hybrids, and electric vehicles.

Frequently Asked Questions

Fill your tank completely, reset your trip odometer (or note the mileage), drive normally until you need to refuel, fill up completely again, and note how many gallons it took. Divide the miles driven by gallons used. For example, 350 miles divided by 12.5 gallons equals 28 MPG. For the most accurate result, repeat this over 3-4 fill-ups and average the results.

For a gasoline car, 30+ MPG combined is considered good, 35+ is very good, and 40+ is excellent. Compact cars typically get 30-40 MPG, mid-size sedans 28-35 MPG, small SUVs 25-32 MPG, and full-size trucks 18-24 MPG. Hybrids regularly achieve 45-55 MPG. The EPA average fuel economy for new cars sold in 2024 is about 26 MPG.

EPA ratings are based on standardized laboratory tests that may not reflect your actual driving conditions. Real-world MPG is typically 10-20% lower than the EPA combined rating. Factors that reduce actual MPG include aggressive driving, city driving with frequent stops, cold weather, using air conditioning, short trips where the engine does not fully warm up, roof racks, and under-inflated tires.

MPG (miles per gallon) is used in the US and measures how far you travel on one gallon of fuel. L/100km (liters per 100 kilometers) is used in most other countries and measures how much fuel you use to travel 100 km. They are inversely related: higher MPG is better, but lower L/100km is better. To convert: L/100km = 235.215 / MPG, and MPG = 235.215 / L/100km.

City driving typically uses 20-30% more fuel than highway driving. Stop-and-go traffic, frequent acceleration, and idling all reduce MPG. Highway driving at steady speeds is more efficient because the engine operates at optimal RPM. However, driving above 60 mph on the highway also reduces efficiency. The sweet spot for most vehicles is 45-55 mph, where aerodynamic drag is manageable and the engine is in its efficient operating range.