Fuel & Efficiency Calculator
MPG & Fuel Cost Calculator
Calculate real-world fuel efficiency, cost per mile, monthly fuel spend, and annual fuel budget. Switch between MPG and metric instantly.
Fill-up Details
Fuel Efficiency
miles per gallon
L/100km
8.4
Cost per Mile
$0.12
Fill-up Cost
$43
Miles / Tank (~13 gal)
364
US Average Gas Prices
US average · June 2025
How MPG is calculated.
L/100km = 235.214 ÷ MPG
Cost per Mile = Gas Price ÷ MPG
Monthly Cost = Cost per Mile × Monthly Miles
What is average MPG in the US?
The average new car sold in the US gets about 28–30 MPG combined (EPA 2024). Sedans typically reach 35–45 MPG, SUVs/trucks 18–25 MPG, and hybrid vehicles 45–60+ MPG.
Real-world vs EPA MPG
Most drivers see 10–20% lower MPG than the EPA estimate due to aggressive driving, AC use, cargo weight, and cold weather. Use this calculator with your actual fill-up data for the most accurate result.
Frequently asked questions.
How do I calculate MPG from a fill-up?
Note your odometer when you fill up, drive normally, then fill up again. Divide the miles you drove by the gallons it took to fill the tank. That's your real-world MPG for that tank.
What is a good MPG for a car?
In the US: above 35 MPG is excellent for a gas car, 28–35 MPG is average, below 20 MPG is typical for trucks/large SUVs. For EVs, equivalent MPGe ratings are often 80–130+.
How much does gas cost per month for an average driver?
The average American drives ~1,200 miles/month. At 28 MPG and $3.45/gallon, that's about $148/month or $1,775/year. Your actual cost depends on local gas prices.
How do I convert MPG to L/100km?
Use the formula: L/100km = 235.214 ÷ MPG. So 30 MPG ≈ 7.8 L/100km. Lower L/100km is better (more efficient).
Why is my real MPG lower than the EPA rating?
EPA figures come from controlled lab tests. Real-world driving involves cold starts, stop-and-go traffic, air conditioning, highway speeds above 65 mph, roof racks, and extra cargo — all of which cut efficiency. It's normal to see 10–20% below the sticker number, which is exactly why measuring your own MPG from a fill-up is more useful.
How can I improve my gas mileage?
The cheapest gains come from keeping tires properly inflated, driving smoothly (gentle acceleration and braking), slowing down on the highway, removing roof racks and unnecessary weight, and staying on top of air filters and tune-ups. Combining trips so the engine runs warm also helps noticeably in cold weather.