# How to estimate fuel costs before you leave

> A three-number formula and how to use it in the planner. – Road trip & camping planner for the USA and Europe.

Source: https://camping-spirit.com/magazine/fuel-costs/

*By CampingSpirit Editors, 2026-07-01*

Fuel is often the biggest variable cost on a road trip, and it is easy to estimate. You need three numbers: the distance, your vehicle's real-world fuel economy and a typical fuel price.

## The formula

Divide the miles by the miles per gallon, then multiply by the price per gallon. A 1,200-mile trip in a car that gets 30 mpg, with gas at $3.50, costs about $140. A motorhome that gets 9 mpg would spend about $467 on the same trip.

## Be honest about MPG

Rated fuel economy assumes gentle driving. Mountain passes, headwinds, a loaded roof box or a trailer can cut it by 20 to 40 percent. Use your own logged average if you have one.

## In the planner

Add your vehicle in Account → Vehicles. The trip's Details tab will then work out fuel for every leg, using the fuel price from your preferences.