Gas Mileage Calculator – MPG & Trip Cost

Whether you want to track your car’s true fuel efficiency, plan the cost of a long road trip, or compare gas vs. electric annual savings, this free Gas Mileage Calculator covers all three scenarios. The Calculate MPG tab computes your miles per gallon from a real fill-up — just enter miles driven and gallons used — and estimates how much you spend on gas per year at current prices. The Trip Cost tab calculates total fuel cost for any route, with per-person split and round-trip totals, so you can budget before you leave. The Gas vs. Electric tab shows you exactly how much you could save annually by switching to an EV, factoring in electricity cost per mile.

Gas mileage — also called fuel economy or MPG (miles per gallon) — directly affects how much you spend every time you fill up. The U.S. average is around 26 MPG for passenger vehicles, but real-world numbers vary widely by vehicle type, driving style, and road conditions. Use this calculator to see where your car stands, identify potential savings, and make smarter decisions at the pump.

How the Gas Mileage Calculator Works

This tool has three modes. The Calculate MPG tab divides your miles driven by gallons used to give your real-world fuel efficiency — more accurate than EPA sticker estimates. Enter your annual mileage to also see estimated annual and monthly fuel costs. The Trip Cost tab estimates how much gas you’ll spend on any journey and splits the cost by number of passengers, including round-trip totals. The Gas vs. Electric tab compares your current annual fuel spending to what you’d spend charging an EV at your local electricity rate, with a 5-year savings projection.

Example 1: Calculating MPG from a fill-up

You fill up, reset your odometer, drive until empty, then fill up again: 340 miles driven, 11.8 gallons used. MPG = 340 ÷ 11.8 = 28.8 MPG. At $4.45/gal with 13,000 miles/year: annual cost = (13,000 ÷ 28.8) × $4.45 = $2,008/year (~$167/month).

Example 2: Road trip New York to Miami

Distance: 1,280 miles. Car gets 30 MPG. Gas: $4.45/gal. 3 passengers. Gallons needed = 1,280 ÷ 30 = 42.7 gal. Total cost = 42.7 × $4.45 = $190. Per person = $63. Round trip = $380 total ($127/person).

MPG Reference by Vehicle Type

Vehicle Type	Typical MPG	Est. Annual Cost (13k mi, $4.45)
Compact car	28–35 MPG	$1,650–$2,065
Midsize sedan	25–32 MPG	$1,808–$2,314
SUV / crossover	20–28 MPG	$2,065–$2,893
Pickup truck	15–22 MPG	$2,630–$3,857
Hybrid	45–58 MPG	$997–$1,284
Electric vehicle	3–4 mi/kWh	~$520–$693 (at $0.16/kWh)

Tips to Improve Your Gas Mileage

Small driving habit changes can add up to significant fuel savings over time. Keep tires properly inflated — under-inflated tires can reduce MPG by up to 3%. Avoid aggressive acceleration and hard braking; smooth, steady driving can improve fuel economy by 15–30% on the highway. Reduce highway speed — fuel efficiency drops sharply above 55 mph, and driving at 70 mph instead of 60 mph can cut MPG by around 17%. Remove excess weight from your trunk; an extra 100 lbs reduces MPG by about 1%. Finally, keep up with regular maintenance: a clogged air filter, worn spark plugs, or old motor oil all hurt fuel economy. Use the MPG Calculator above after making any of these changes to measure your real improvement over time.

Frequently Asked Questions

How do I calculate my car’s MPG?

Divide the number of miles driven by the gallons of gas used. For example, if you drove 350 miles and used 12 gallons, your MPG is 350 ÷ 12 = 29.2 MPG. For the most accurate result, fill up completely, reset your trip odometer, drive normally, then fill up again and record miles driven and gallons pumped. The calculator above does this math instantly.

What is a good MPG for a car in 2025?

For a non-hybrid gas vehicle, 30–35 MPG combined is considered good. Compact cars and sedans typically achieve 32–40 MPG, while SUVs and trucks average 20–28 MPG. Hybrids range from 45–55 MPG and plug-in hybrids can exceed 60 MPGe. The EPA fuel economy standard for new vehicles sold in the U.S. is moving toward 49 MPG by 2026.

How much does the average American spend on gas per year?

The average U.S. driver spends approximately $2,000–$3,000 per year on gasoline, based on roughly 15,000 miles driven annually at an average of 26 MPG and a gas price around $3.20–$3.50 per gallon. Higher-mileage drivers or those with lower-MPG vehicles can spend considerably more. Use the Trip Cost tab above to estimate your own annual fuel spending.

Is gas or electric cheaper to drive?

In most U.S. states, electric vehicles (EVs) cost significantly less per mile to operate. At the national average electricity rate (~$0.16/kWh), an EV costs roughly $0.04–$0.05 per mile, compared to $0.10–$0.14 per mile for a 30 MPG gas vehicle at $3.30/gallon. The Gas vs. Electric tab in this calculator shows your personalized annual savings based on your actual driving habits.

Does city vs. highway driving affect MPG?

Yes, significantly. Highway driving at steady speeds is generally 20–40% more fuel-efficient than city driving, which involves frequent stops, idling, and short acceleration bursts. Most manufacturers report separate city and highway EPA ratings for this reason. Many modern vehicles with start-stop technology and hybrid systems narrow this gap by recovering energy during braking.

What factors affect my car’s fuel economy the most?

The biggest factors are driving speed (fuel consumption rises sharply above 55 mph), acceleration and braking habits, vehicle weight, tire pressure, air conditioning use, and aerodynamic drag. Engine size and vehicle type are also major determinants — a V8 truck will always use more fuel than a 4-cylinder sedan regardless of driving style. Regular maintenance such as clean air filters and properly inflated tires helps maintain peak efficiency.

How do I calculate the fuel cost of a road trip?

Divide the total trip distance by your car’s MPG to get gallons needed, then multiply by the current gas price. For example: 600 miles ÷ 30 MPG = 20 gallons × $3.40 = $68. The Trip Cost tab in this calculator does this automatically and also splits the total among passengers, making it easy to plan cost-sharing for group travel.

Can I improve MPG without buying a new car?

Yes. Common improvements include: keeping tires inflated to the recommended PSI (can add 1–3 MPG), replacing a clogged air filter (can restore up to 10% efficiency), using the manufacturer’s recommended motor oil grade, removing roof racks or cargo boxes when not in use, and using cruise control on highways to maintain a steady speed. Combining errands into fewer trips also helps since cold engines burn more fuel.