Calculate Fuel Economy
Fuel Economy Reference
| Vehicle Type | MPG (US) | L/100km |
|---|---|---|
| Hybrid / Electric | 50-60+ | 3.9-4.7 |
| Compact Car | 30-40 | 5.9-7.8 |
| Midsize Sedan | 25-35 | 6.7-9.4 |
| SUV / Crossover | 20-28 | 8.4-11.8 |
| Pickup Truck | 15-22 | 10.7-15.7 |
| Sports Car | 18-28 | 8.4-13.1 |
How to Calculate Fuel Economy
Calculating your vehicle's fuel economy is straightforward:
MPG Formula (US)
MPG = Distance (miles) ÷ Fuel Used (gallons)
L/100km Formula (Metric)
L/100km = (Fuel Used (liters) × 100) ÷ Distance (km)
Tips for Accurate Measurement
- Fill-to-fill method: Fill your tank completely, reset your trip odometer, drive normally, then fill up again. Record the miles driven and gallons added.
- Multiple tanks: For more accuracy, track over 3-5 fill-ups and average the results.
- Consistent conditions: Highway driving gives better MPG than city driving. Temperature and AC use also affect economy.
Unit Conversions
- MPG to L/100km: L/100km = 235.215 ÷ MPG
- L/100km to MPG: MPG = 235.215 ÷ L/100km
- 1 US gallon = 3.785 liters
- 1 mile = 1.609 km
Frequently Asked Questions
How do I calculate my car's MPG?
Divide the total miles driven by the gallons of fuel used. For example, if you drove 300 miles and used 10 gallons, your fuel economy is 300 ÷ 10 = 30 MPG. For the most accurate reading, use the fill-to-fill method: fill your tank, drive normally, fill up again, and divide miles driven by gallons added.
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.
What is a good MPG for a car?
It depends on the vehicle type. For a passenger car, 30+ MPG is considered good and 40+ MPG is excellent. SUVs typically get 20–28 MPG, and pickup trucks 15–22 MPG. Hybrids often achieve 45–58 MPG. See the reference table above for more ranges.
Why is my real MPG lower than the EPA estimate?
EPA tests use controlled conditions — moderate temperature, no wind, standardized driving patterns. Real-world factors like aggressive acceleration, cold weather, short trips, air conditioning, extra cargo weight, and hilly terrain all reduce fuel economy, typically by 10–20% below EPA ratings.
How do I calculate fuel cost for a road trip?
Divide the trip distance by your MPG to get gallons needed, then multiply by the fuel price. Example: a 450-mile trip at 28 MPG with gas at $3.40/gallon = 450 ÷ 28 × $3.40 = $54.64. For a metric calculation, use (distance km ÷ 100) × L/100km × price per liter.
What is the most accurate way to measure fuel economy?
The fill-to-fill method is the standard. Fill your tank completely, reset your trip odometer, drive normally, then fill up again at the same pump. Divide miles driven by gallons added. For best accuracy, average the results over 3–5 fill-ups. In-dash trip computers are typically optimistic by 5–15%.
Does driving speed affect fuel economy?
Yes, significantly. Most vehicles reach peak efficiency between 35–50 mph (55–80 km/h). Above 50 mph, aerodynamic drag increases with the square of speed, and every additional 5 mph costs roughly 7–14% more fuel depending on the vehicle.
Does tire pressure affect gas mileage?
Yes. Under-inflated tires increase rolling resistance. Each 1 PSI drop below the recommended pressure reduces fuel economy by about 0.2%. Tires that are 8 PSI low — common in cold weather — can cost 1.5% or more in efficiency.
Learn more about measuring and improving fuel economy in our guide: How to Calculate Fuel Economy — MPG, L/100km, and What Actually Affects Gas Mileage
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are estimates and may vary based on actual conditions.
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Fuel Economy Calculator FAQ
How do I calculate my car's MPG?
Divide the total miles driven by the gallons of fuel used. For example, if you drove 300 miles and used 10 gallons, your fuel economy is 300 ÷ 10 = 30 MPG.
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.
What is a good MPG for a car?
For a passenger car, 30+ MPG is considered good and 40+ MPG is excellent. SUVs typically get 20–28 MPG, and pickup trucks 15–22 MPG. Hybrids often achieve 45–58 MPG.
Why is my real MPG lower than the EPA estimate?
EPA tests use controlled conditions — moderate temperature, no wind, standardized driving. Real-world factors like aggressive acceleration, cold weather, short trips, air conditioning, extra cargo weight, and hilly terrain all reduce fuel economy, typically by 10–20% below EPA ratings.
How do I calculate fuel cost for a road trip?
Divide the trip distance by your MPG to get gallons needed, then multiply by the fuel price. Example: a 450-mile trip at 28 MPG with gas at $3.40/gallon costs 450 ÷ 28 × $3.40 = $54.64.
What is the most accurate way to measure fuel economy?
Use the fill-to-fill method: fill your tank, reset the trip odometer, drive normally, then fill up again. Divide miles driven by gallons added. For best accuracy, average the results over 3–5 fill-ups.