Free tools · Road trips
Gas trip cost calculator
Enter the distance, your car's mpg, and the local gas price. Get the fuel cost for the drive — split evenly between everyone in the car, tolls included.
Free · No account · Nothing saved
3 pay $15.43 · 1 pay $15.42 — the total works out exactly.
The road-trip gas math
The formula is three numbers deep: (miles ÷ mpg) × price per gallon. A 240-mile drive each way — 480 miles round trip — in a 28 mpg car at $3.60 a gallon burns about 17.1 gallons, or roughly $61.71 of fuel. Four people in the car makes that about $15.43 each, and this calculator assigns the stray pennies so the total works out exactly.
Two things people forget: tolls and parking often rival the fuel cost on shorter trips (there’s a field for them above), and fuel is only the visible half of what driving costs — depreciation, tires, and maintenance roughly double it, which is why the friend who always drives deserves at least the good playlist and first pick of snacks.
Gas is usually just the first shared expense of a trip. For the motel, the groceries, and the boat tour only half the group did, our trip expense splitter handles the whole weekend — and Split! keeps a running tab in real time.
Frequently asked questions
How do you calculate the gas cost of a trip?+
Divide the trip distance by your car's fuel economy to get gallons, then multiply by the gas price: (miles ÷ mpg) × price per gallon. A 480-mile round trip in a 28 mpg car at $3.60 per gallon uses about 17.1 gallons and costs about $61.71 in fuel.
How should we split gas on a road trip?+
The most common convention is an even split between everyone in the car, driver included — the driver is going anyway, but everyone shares the ride. Some groups have passengers cover all the fuel as thanks for the driver providing the car. Either way, agree before the trip and this calculator gives you the per-person number.
Should the driver pay less because it's their car?+
There's a fair argument for it: fuel is only part of the cost of driving. The IRS standard mileage rate (70¢ per mile for 2025) prices the all-in cost — fuel plus depreciation, tires, insurance, and maintenance — at roughly double the fuel-only cost. Splitting fuel evenly while the driver absorbs the wear is already a good deal for passengers; generous groups split fuel among passengers only.
What fuel economy number should I use?+
Your car's trip computer average is best; otherwise use the EPA combined rating for your model (fueleconomy.gov lists every car). Highway-heavy trips usually beat the combined number — most cars land somewhere between 25 and 35 mpg on the open road.
Does this work for an electric car?+
The structure is the same — energy used × price — but the units differ (kWh per mile and price per kWh). As a rough workaround, divide your EV's miles-per-kWh into the distance and multiply by your electricity rate.
Is this gas calculator free?+
Yes — free, no account, nothing stored. The math runs in your browser.
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