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Work out how much fuel a road trip will burn through, in money terms.
Tip: if you know your car's efficiency in miles per gallon instead, roughly divide mpg by 2.35 to convert to km per litre before entering it.
Fuel is the cost road-trippers most often estimate by gut feeling rather than arithmetic, and it's usually the second-largest expense of a road trip after accommodation. The actual formula is simple — distance divided by fuel efficiency gives litres needed, multiplied by the price per litre gives total cost — but people rarely sit down and do it before setting off, then get an unpleasant surprise partway through a long trip when fuel spend runs ahead of what they'd mentally budgeted.
Fuel efficiency figures quoted by manufacturers are measured under controlled test conditions and are almost always a bit optimistic compared with real mixed-terrain driving, especially once you factor in a fully loaded car, mountain roads, or running the air conditioning hard in hot weather. A more reliable number comes from your own car's recent fill-up history: divide the distance driven since your last full tank by the litres it took to fill it back up, and use that real-world figure rather than the manufacturer's spec sheet number for a more accurate cost estimate.
Fuel prices can differ meaningfully even within the same country, let alone across a border on an international road trip — rural fuel stations along a highway often charge more than in cities due to lower competition and higher delivery costs, while some countries deliberately keep fuel subsidised well below what a neighbouring country charges. If your route crosses regions or countries with noticeably different fuel prices, it's worth running this calculator with the higher expected price to get a safer upper-bound budget, then adjusting downward if you end up filling up somewhere cheaper.
Group road trips often split across two or more cars rather than everyone squeezing into one, and this calculator's vehicle count field multiplies the total fuel cost across however many vehicles you're running, assuming they cover the same distance and have similar efficiency. If your vehicles have meaningfully different efficiency — say a fuel-efficient sedan alongside a larger SUV — it's more accurate to run the calculator twice, once per vehicle, and add the two totals together.
Fuel is only one line item in a road trip's total cost, alongside tolls, parking and the meals and stays along the way. Once you know the fuel cost, feed the full route into the Road Trip Route Planner to check drive time and whether an overnight stop is needed, and use the Trip Cost Splitter afterward if the group wants to split fuel and other costs fairly rather than by who happened to pay at each stop.
Worth remembering as well: driving style has a real effect on real-world fuel efficiency — aggressive acceleration and high sustained speeds on highways both increase consumption noticeably compared with steady, moderate-speed driving, so a road trip driven gently can come in meaningfully under this calculator's estimate if it's based on your car's average rather than best-case efficiency.
Check your car's manual for a manufacturer figure, but for a more realistic number divide the distance since your last full tank by the litres used to refill it, since real driving conditions are usually less efficient than lab test figures.
Roughly divide the mpg figure by 2.35 to get an approximate km-per-litre figure suitable for this calculator.
No, this calculator covers fuel only. Add tolls, parking and any ferry crossings separately in your overall trip budget.
Use your best estimate of the price you'll actually be paying along the route — for a multi-country trip, running the calculation with the highest expected price gives you a safer budget ceiling.