Fuel Cost Calculator
Work out how much fuel your trip will cost and how many gallons you'll burn from distance, MPG, and gas price.
Example
A 300-mile one-way trip in a car that gets 28 MPG with gas at $3.50/gal uses 300 / 28 = 10.71 gallons, costing 10.71 x $3.50 = $37.50 (about $0.13 per mile).
How it works
Gallons used = distance / MPG, and total cost = gallons x price per gallon. For a round trip the distance is doubled before the calculation.
Good to know
The Fuel Cost Calculator estimates what a drive will cost in gas and how much fuel you'll burn, using three numbers you already know or can look up: trip distance in miles, your vehicle's fuel efficiency in miles per gallon (MPG), and the current price per gallon. It's built for commuters comparing routes, road trippers budgeting a long haul, and anyone splitting gas money with passengers.
Reach for it before a trip when you want a quick budget figure, or after one to check whether the drive was worth it versus other options. Because it shows cost per mile alongside the total, it's also handy for comparing two cars or two routes: a more fuel-efficient vehicle or a shorter path will visibly lower the per-mile number even when total distance stays the same.
To read the result, start with the big "Total fuel cost" figure, then sanity-check the supporting stats. "Gallons used" is distance divided by MPG; "Effective distance" reflects the doubled mileage if you switched on Round trip; and "Cost per mile" is the total divided by that effective distance, which is the cleanest way to compare trips of different lengths. If any number looks off, the usual culprit is an MPG that doesn't match real driving conditions.
One practical caveat: the EPA or window-sticker MPG is often optimistic. Highway cruising can beat it, while city traffic, heavy loads, cold weather, roof racks, or aggressive driving can drop real-world mileage by 20% or more. For a budget you won't blow through, plug in your own observed MPG from a recent tank rather than the rated figure, and round the gas price up a few cents to leave a margin.
Frequently asked questions
Does this include a round-trip option?
Yes. Toggle to Round trip and the calculator doubles your distance before computing gallons and cost, so you see the full there-and-back total.
What if I only know liters or kilometers?
This tool uses miles, MPG, and price per gallon. Convert first: 1 km is about 0.621 miles and 1 gallon is about 3.785 liters, then enter the converted values.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Your inputs never leave your device, and it works offline once loaded.
Is this calculator free?
Yes, completely free with no sign-up and no limits.
People also ask
How do I calculate gas cost for a trip by hand?
Divide the trip distance by your vehicle's MPG to get gallons used, then multiply that by the price per gallon. For example, 300 miles at 28 MPG is about 10.71 gallons, and at $3.50 per gallon that comes to roughly $37.50.
What MPG should I use for the most accurate estimate?
Use your real-world MPG measured from a recent fill-up rather than the window-sticker rating, since actual mileage often runs lower. To measure it, fill the tank, reset the trip odometer, drive normally, then divide miles driven by gallons added at the next fill-up.
How do I split gas money fairly among passengers?
Calculate the total fuel cost for the trip, then divide it by the number of people sharing the ride, including or excluding the driver based on what the group agrees. The cost-per-mile figure also helps if some passengers only ride part of the way.
Does air conditioning or driving fast increase fuel cost?
Yes, both can raise consumption. Running A/C and driving at high speeds increase aerodynamic drag and engine load, which lowers MPG, so your real fuel cost may exceed an estimate based on rated mileage.
How much does a long road trip cost in gas?
Multiply the total round-trip distance by the price per gallon, then divide by your MPG. A 1,000-mile round trip at 30 MPG with gas at $3.50 would use about 33 gallons and cost roughly $117.
Is it cheaper to drive or fly for a given distance?
For driving, this calculator gives the fuel cost, but a full comparison should also factor in tolls, parking, vehicle wear, and time, versus a flight's ticket price and airport transfers. Shorter trips and multiple passengers usually favor driving, while long solo trips often favor flying on cost alone.
How does fuel price affect the total compared to distance?
Total cost scales directly with both price per gallon and distance, so a 10% rise in gas price raises the total by 10%, just as adding 10% more miles would. Improving MPG is the only one of the three inputs that lowers cost without changing your trip or the pump price.
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