Road Trip Fuel Planner

How it works

Driving time is the distance divided by your average speed, and the fuel used is the distance divided by MPG. Fuel cost is the gallons times the price, split evenly among the people sharing it.

Fuel stops assume you leave with a full tank and refuel each time you have used the usable share of the tank. The miles between stops are tank capacity × MPG × usable share. The trip needs as many tankfuls as the distance divided by that, rounded up; the first comes from the tank you start with, so the stops are one fewer. A trip that ends exactly as a leg runs out counts no extra stop.

A usable share below 100% plans each stop before the tank runs low. At 100% the miles between stops equal the full-tank range that fueleconomy.gov lists, which assumes every gallon is used.

Formula

driving time      = distance ÷ average speed
gallons           = distance ÷ MPG
fuel cost         = gallons × price
cost per person   = fuel cost ÷ people
miles per tank    = tank capacity × MPG × usable % ÷ 100
fuel stops        = ceil(distance ÷ miles per tank) − 1

Example

A 600-mile trip at an average 60 mph takes 10 hours of driving. At 30 mpg it burns 20 gallons, which at $3.50 a gallon is $70.00, or $35.00 each for two people.

With a 15-gallon tank used down to 75% before each stop, the car covers 15 × 30 × 0.75 = 337.5 miles between stops. 600 ÷ 337.5 = 1.78, which rounds up to 2 tankfuls: the one you leave with and 1 fuel stop.

Assumptions and limitations

• Average speed and MPG are held constant for the whole trip. Real speed depends on traffic, weather, terrain and rest breaks; real MPG on speed, load and climate control. Driving time excludes stops.
• The trip starts with a full tank, and every stop refills it. Station spacing is not considered: on remote routes the next station may be closer or farther than the plan assumes.
• Fuel cost counts all fuel burned on the trip at one price, including fuel still in the tank from before departure; prices along a route differ.
• The usable share and the fuel price defaults are illustrative. This is a planning estimate, not navigation or a guarantee of range.

Frequently asked questions