Estimate fuel required and fuel cost from trip distance, vehicle efficiency and your fuel price.
Method
Metric: liters used = distance × L/100 km ÷ 100. US: gallons used = miles ÷ mpg. Cost = fuel used × fuel price.
Example: 500 km at 7 L/100 km uses 35 L.
Scope
Use your own fuel price. Traffic, terrain, weather, load and driving style can change real consumption.