Practical guide
How to Calculate Fuel Cost for a Trip
Fuel litres = one-way distance × journeys ÷ 100 × litres per 100 km × (1 + buffer ÷ 100). Fuel cost = litres × price. Cost per km = cost ÷ distance before the buffer. Cost per person = cost ÷ people.
Updated 14 October 2026
Worked example (illustration only)
100 km at 8 L/100 km and R20/litre needs 8 litres and costs R160, or R1.60/km. Two journeys with a 10% fuel allowance need 17.6 litres and cost R352; two people pay R176 each. R20 is an example, not today’s price.
Check the inputs
Enter one-way kilometres and journeys (2 for return). Choose L/100 km or km per litre, enter your measured fuel use, select the fuel grade and enter your pump price and its date. Add a fuel allowance, sharing and repeat trips if needed.
What to check before relying on the result
Fuel only: tolls, parking, accommodation and maintenance are excluded. The buffer increases litres; it does not change the physical distance. Weekly repeat counts apply to the complete trip already defined by journeys. Average monthly cost uses 52 ÷ 12 weeks.
How to measure your fuel use
Fill the tank, record kilometres, drive normally and refill. Litres added ÷ kilometres travelled × 100 gives L/100 km. Convert km per litre with 100 ÷ km per litre; 12.5 km/L equals 8 L/100 km.
Petrol and diesel prices
Use the actual price for your required grade and location. Selecting the fuel grade does not load a price. Official diesel schedules describe wholesale prices; your retail pump price may differ.
Use the related calculators
Apply the explanation above with your own figures. Open a calculator below, check every input and review the result assumptions before making a decision.
Official information
Calculation and text reviewed; use the linked provider for current rules and quotes. See Department of Mineral and Petroleum Resources fuel prices. Rules, rates and institutional requirements can change, so confirm time-sensitive information at the official source.