Gas Mileage Calculator
Calculate your vehicle's fuel efficiency, estimate trip fuel costs, view annual fuel expenses, and compare gas mileage between two vehicles. Supports both US (MPG) and metric (L/100km) units.
Average American drives ~13,500 miles/year
Vehicle A
Vehicle B
Average Fuel Efficiency by Vehicle Type
Use these reference values to see how your vehicle compares to typical averages (2024 EPA estimates).
| Vehicle Type | MPG (US) | L/100km | Annual Fuel Cost* |
|---|---|---|---|
| Compact Car | 30 -- 35 | 6.7 -- 7.8 | $1,200 -- $1,575 |
| Midsize Sedan | 27 -- 32 | 7.4 -- 8.7 | $1,340 -- $1,750 |
| Full-size Sedan | 24 -- 29 | 8.1 -- 9.8 | $1,550 -- $1,970 |
| Small SUV / Crossover | 26 -- 31 | 7.6 -- 9.0 | $1,400 -- $1,820 |
| Midsize SUV | 22 -- 27 | 8.7 -- 10.7 | $1,650 -- $2,150 |
| Full-size SUV | 17 -- 22 | 10.7 -- 13.8 | $2,150 -- $2,780 |
| Pickup Truck | 18 -- 24 | 9.8 -- 13.1 | $1,970 -- $2,630 |
| Minivan | 22 -- 28 | 8.4 -- 10.7 | $1,690 -- $2,150 |
| Hybrid | 45 -- 55 | 4.3 -- 5.2 | $860 -- $1,050 |
| Sports Car | 20 -- 28 | 8.4 -- 11.8 | $1,690 -- $2,360 |
*Annual cost assumes 13,500 miles/year at $3.50/gallon. Actual mileage varies by driving conditions, maintenance, and driving habits.
How to Improve Your Gas Mileage
Small changes in driving habits and vehicle maintenance can make a measurable difference in fuel efficiency. Here are proven strategies:
Maintain Proper Tire Pressure
Under-inflated tires increase rolling resistance and waste fuel. Check pressure monthly and match the value on your door jamb sticker.
Drive Smoothly
Avoid aggressive acceleration and hard braking. Gradual speed changes keep your engine in efficient RPM ranges.
Reduce Highway Speed
Aerodynamic drag increases exponentially with speed. Driving 55 mph instead of 70 mph can significantly reduce fuel consumption.
Use Cruise Control
Maintaining constant speed on the highway avoids the fuel waste from speed fluctuations.
Remove Excess Weight
Every 100 lbs (45 kg) of extra weight reduces MPG by about 1%. Clear out cargo you do not need.
Keep Up with Maintenance
Replace air filters, use the recommended motor oil grade, and fix engine issues promptly. A tuned engine runs more efficiently.
Minimize Idling
Idling wastes fuel and produces emissions. Turn off the engine if you expect to wait more than 30 seconds.
Remove Roof Racks
Roof racks and cargo carriers increase aerodynamic drag, even when empty. Remove them when not in use.
How Gas Mileage is Calculated
MPG (Miles Per Gallon) -- US Standard
MPG = Distance (miles) / Fuel Used (gallons)
Example: 350 miles on 12.5 gallons = 350 / 12.5 = 28 MPG
L/100km (Liters per 100 Kilometers) -- Metric Standard
L/100km = (Fuel Used (L) / Distance (km)) x 100
Example: 40 liters over 500 km = (40 / 500) x 100 = 8.0 L/100km
Converting Between MPG and L/100km
L/100km = 235.215 / MPG | MPG = 235.215 / L/100km
The constant 235.215 comes from the conversion between miles/gallons and km/liters. Higher MPG means better efficiency; lower L/100km means better efficiency.
Trip Fuel Cost
Fuel Cost = (Distance / Fuel Efficiency) x Fuel Price
For US units: Cost = (Miles / MPG) x Price per Gallon. For metric: Cost = (km / 100) x L/100km x Price per Liter.
Frequently Asked Questions
How do I calculate gas mileage (MPG)?
Fill up your tank completely, reset your trip odometer, and drive normally. At your next fill-up, note the miles driven and gallons pumped. Divide miles by gallons to get your MPG. For example, 300 miles on 10 gallons = 30 MPG.
How do I calculate fuel efficiency in L/100km?
Divide the liters of fuel used by the distance in kilometers, then multiply by 100. For example, using 40 liters over 500 km gives (40 / 500) x 100 = 8.0 L/100km. Lower numbers mean better efficiency.
What is a good MPG for a car?
A good MPG depends on vehicle type. Compact cars average 30--35 MPG, midsize sedans 27--32 MPG, SUVs 23--28 MPG, and trucks 18--24 MPG. Hybrids typically achieve 45--55 MPG. Any vehicle exceeding its class average is considered fuel-efficient.
How can I improve my gas mileage?
The most effective methods are maintaining proper tire pressure (up to 3% improvement), driving smoothly without aggressive acceleration (up to 33% on highways), using cruise control, reducing excess weight, keeping up with engine maintenance, and minimizing idling.
How do I convert MPG to L/100km?
Divide 235.215 by the MPG value. For example, 30 MPG = 235.215 / 30 = 7.84 L/100km. To convert the other way, divide 235.215 by the L/100km value. This constant accounts for the conversion between miles, kilometers, gallons, and liters.
Why does my actual MPG differ from the EPA estimate?
EPA estimates are based on standardized lab tests. Real-world factors like aggressive driving, city vs highway mix, weather, terrain, cargo weight, tire condition, and air conditioning use all affect actual fuel economy. Most drivers achieve 10--20% below EPA estimates in mixed driving.
Does speed affect gas mileage?
Yes. Most vehicles reach peak fuel efficiency between 35--45 mph. Above 50 mph, fuel efficiency drops due to increased aerodynamic drag. Every 5 mph over 50 mph is roughly equivalent to paying an extra $0.15--$0.30 per gallon.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.
Privacy & Limitations
Privacy: This calculator runs entirely in your browser. No personal data is transmitted or stored anywhere.
Limitations: Fuel efficiency varies based on driving conditions, vehicle maintenance, terrain, weather, and driving habits. The values calculated here are estimates. CO2 emission estimates use an average of 8.887 kg CO2 per gallon of gasoline (EPA figure) and should be treated as approximations.
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Gas Mileage Calculator FAQ
How do I calculate gas mileage (MPG)?
Divide the distance traveled (in miles) by the amount of fuel used (in gallons). For example, if you drove 300 miles on 10 gallons, your fuel efficiency is 300 / 10 = 30 MPG.
How do I calculate fuel efficiency in L/100km?
Divide the fuel used (in liters) by the distance traveled (in km), then multiply by 100. For example, 40 liters used over 500 km = (40 / 500) x 100 = 8.0 L/100km.
What is a good MPG for a car?
A good MPG depends on vehicle type. Compact cars average 30-35 MPG, midsize sedans 27-32 MPG, SUVs 23-28 MPG, and trucks 18-24 MPG. Hybrids typically achieve 45-55 MPG, and plug-in hybrids can exceed 60 MPGe.
How can I improve my gas mileage?
Key ways to improve fuel efficiency include maintaining proper tire pressure, removing excess weight, avoiding aggressive acceleration and braking, using cruise control on highways, keeping up with engine maintenance, and reducing idling time.
How do I convert MPG to L/100km?
To convert MPG to L/100km, divide 235.215 by the MPG value. For example, 30 MPG = 235.215 / 30 = 7.84 L/100km. To convert L/100km to MPG, divide 235.215 by the L/100km value.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.