Car Fuel Mileage Calculator: MPG, Cost & L/100km (2026)
Track your actual MPG, L/100km, trip costs, and per-mile fuel expenses. Works with miles/km and gallons/liters in seconds.
What Is Fuel Mileage and Why It Matters
Fuel mileage measures how far your car travels per unit of fuel. In the US, it’s MPG (miles per gallon). Most other countries use L/100km (liters per 100 kilometers). Higher MPG = better efficiency, while lower L/100km = less fuel used.
For example: a car that drives 300 miles on 10 gallons gets 30 MPG. If you drive 15,000 miles yearly at $3.50/gal, improving from 25 MPG to 30 MPG saves over $350 per year. FuelEconomy.gov confirms that small efficiency gains add up fast.
Ignoring your fuel mileage can hide costly issues: low tire pressure, dirty air filters, or poor driving habits. Tracking regularly helps you catch problems early.
The Formula Explained
L/100km = (Fuel in liters ÷ Distance in km) × 100
Trip cost = Fuel used × Price per unit
Cost per mile/km = Trip cost ÷ Distance
| Term | Meaning |
|---|---|
| MPG | Miles per gallon (US gallon = 3.785 liters) |
| L/100km | Liters per 100 kilometers |
| Trip cost | Total fuel expense for the trip |
| Cost per mile/km | Fuel cost for each distance unit |
Worked example: You drive 150 miles, use 5.5 gallons, price $3.80/gal. MPG = 150÷5.5 = 27.3 MPG. L/100km = (5.5×3.785) ÷ (150×1.609) ×100 = 8.6 L/100km. Trip cost = $20.90 → cost per mile = $0.139.
How to Use This Calculator — Step by Step
- Enter distance traveled – use your trip odometer (miles or km).
- Enter fuel used – fill the tank and record gallons or liters.
- Set fuel price – optional but unlocks cost per mile and trip cost.
- Click Calculate – get instant MPG, L/100km, and total fuel cost.
- Adjust units – switch between mi/km or gal/L to match your region.
Fuel Mileage Reference Table (Real vehicles)
| Vehicle type | MPG (range) | L/100km |
|---|---|---|
| Hybrid compact | 48–56 | 4.2–4.9 |
| Gas sedan | 28–35 | 6.7–8.4 |
| SUV (gas) | 20–26 | 9.0–11.8 |
| Pickup truck | 16–22 | 10.7–14.7 |
| Sports car | 18–24 | 9.8–13.1 |
| Electric (MPGe) | 100–120 MPGe | ~2.0–2.5 L/100km eq. |
Real-World Examples
🚗 Example 1 – Ahmed’s commute: Drives 300 km weekly, uses 22.5 liters, fuel price $1.65/L. Input: 300 km, 22.5 L. MPG = 31.1 MPG, L/100km = 7.5. Trip cost = $37.12, cost per km = $0.124. Ahmed now compares routes.
🚙 Example 2 – Family road trip: 520 miles, 21 gallons, price $4.10/gal. Efficiency = 24.8 MPG (9.5 L/100km). Total fuel cost = $86.10 → per mile = $0.166. Planning next trip, they know a more efficient SUV saves $20.
5 Tips to Improve Your Result
- Keep tires inflated – under-inflated tires lower MPG by up to 3% per 5 PSI below recommended.
- Reduce speed – driving 65 mph vs 75 mph improves fuel economy by about 7-14%.
- Remove roof racks – at highway speeds, empty crossbars reduce MPG by ~2-5%.
- Replace air filter – a clean filter improves acceleration and MPG by up to 10% (especially older cars).
- Avoid aggressive driving – rapid acceleration and braking can lower your MPG by 15-30% at highway speeds.
Frequently Asked Questions
What is a good MPG for a car?
A good MPG (miles per gallon) depends on vehicle type. For a modern compact car, 30-40 MPG is excellent. SUVs typically range 20-28 MPG, while hybrids can exceed 50 MPG. Anything above 25 MPG for mixed driving is considered decent.
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 equals 235.215 ÷ 30 = 7.84 L/100km. Our calculator shows both metrics automatically.
Does my fuel price affect fuel economy calculation?
No, fuel price doesn’t change MPG or L/100km – those measure efficiency. But price helps you estimate trip cost and cost per mile/km, which is critical for budgeting long drives.
Why does my car’s real MPG differ from factory estimates?
Real-world MPG varies due to driving habits (hard acceleration), traffic, tire pressure, AC use, and weather. The EPA estimates are lab-tested, so your actual mileage can be 10-20% lower.
How accurate is this fuel mileage calculator?
It’s very accurate if you enter precise distance and fuel amounts. Use trip odometer and fuel pump readings for best results. The calculator uses standard conversion factors (1 gal = 3.785 L, 1 mile = 1.609 km).
I’m Alex Rahman, a car enthusiast and automotive writer focused on practical solutions, car tools, and real-world driving advice. I share simple and honest content to help everyday drivers make better decisions.