Know before you go: enter the distance, your car's MPG and the gas price — see exactly what the trip costs, split it with passengers, and check what your commute really costs per year.
Assumes 5 driving days per week, 48 working weeks per year.
The formula is simple: distance ÷ MPG × price per gallon. A 300-mile trip in a car that averages 25 MPG needs 12 gallons; at $3.60 a gallon, that's $43.20. What surprises most people isn't the formula — it's seeing the per-year number on a commute they've been driving on autopilot for years.
The EPA rating on the window sticker was measured in a lab. Your real number lives in your trip computer, and it's shaped by how you actually drive: city stop-and-go can run 20% below the combined rating, while steady highway cruising often beats it. Roof boxes, underinflated tires, and a trunk full of junk all quietly tax every mile. If your car doesn't show average MPG, fill the tank, reset the trip odometer, drive normally until the next fill-up, and divide miles driven by gallons pumped — that's your true number.
Total trip cost feels abstract; cost per mile is where the choices get real. At $3.60 per gallon, a 25 MPG sedan costs about 14 cents per mile in fuel. A 15 MPG pickup costs 24 cents — nearly double for every single mile, forever. Over a typical 12,000-mile year that gap is more than $1,100. It's also the honest way to compare driving against flying for a long trip: multiply the round-trip miles by your cost per mile and add one hotel night if it's a two-day drive.
The passenger split in this calculator settles the oldest road-trip argument there is. Gas is the obvious shared cost, but if you want the truly fair number, remember the driver is also donating wear: the IRS values total driving costs at roughly 70 cents per mile for a reason — fuel is only about a fifth of what a car really costs to run.
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