How to Calculate Fuel Cost for a Road Trip (2026)

Estimating fuel cost before a road trip lets you budget accurately, compare routes, and decide whether driving beats flying. The calculation takes three inputs: trip distance, your vehicle's fuel efficiency, and the current fuel price. The Fuel Cost Calculator handles the arithmetic instantly — enter the numbers and get a total cost with a per-mile or per-kilometer breakdown.

The Formula

Fuel cost = (Distance ÷ Fuel Efficiency) × Fuel Price. Distance in miles, efficiency in miles per gallon (MPG), price in dollars per gallon. For metric: distance in kilometers, efficiency in liters per 100 km, price per liter — the formula becomes: Fuel cost = (Distance ÷ 100) × L/100km × Price per liter.

Example: 600-mile drive, 30 MPG vehicle, gas at $3.50/gallon. Gallons needed = 600 ÷ 30 = 20. Total cost = 20 × $3.50 = $70.

Fuel Cost by Vehicle Type — Reference Table

The table below shows estimated fuel cost for a 500-mile trip at $3.50/gallon (electric cost based on $0.14/kWh):

What Affects Real-World Fuel Economy

Your EPA or manufacturer MPG rating is a laboratory figure. Highway cruising at 70–75 mph typically yields 10–15% less than the rated figure due to aerodynamic drag at higher speeds. Air conditioning on a hot day adds another 5–10% penalty. A loaded car or towing a trailer can cut efficiency by 20–30%, so always use a realistic MPG when planning rather than the sticker number.

Elevation gain also matters on mountain routes. A route through the Rockies with several thousand feet of cumulative climb will consume noticeably more fuel than a flat interstate of the same distance. If your route has significant elevation change, add a 10–15% buffer to your estimate.

Splitting Costs and Comparing Routes

Once you have a total fuel cost, dividing by the number of passengers gives you a per-person figure that makes road trips easy to compare against flights or rail. A $90 fuel total split four ways is $22.50 per person — often far cheaper than any alternative for short-to-mid distances.

Use the Fuel Cost Calculator to run both routes side by side and pick the cheaper one. Enter each route's distance separately and compare the totals.