Practical guide
How to Calculate Fuel Cost per Km
Fuel cost per km = litres per 100 km ÷ 100 × pump price. For km per litre, divide the pump price by km per litre.
Updated 14 October 2026
Worked example
Example only: 8 L/100 km at R20/litre is R1.60/km. At 1 000 km per month, fuel costs R1 600.
Measure consumption
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.
Use the result carefully
Use fuel cost per km to compare cars at the same pump price or plan a budget. It excludes maintenance, depreciation, insurance and finance, and is not a SARS rate.
Frequently asked question: does a return trip change cost per km?
It doubles the kilometres and fuel cost at unchanged consumption. The cost per kilometre stays the same.
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
Formula and worked example reviewed. Follow the source for dated official price schedules. See Official fuel-price announcements. Rules, rates and institutional requirements can change, so confirm time-sensitive information at the official source.