Rates & sources
DVLA, HMRC fuel advisory rates and manufacturer-published figures. Real-world results vary by driving style.
Source: DVLA / HMRC fuel advisory rates — figures refreshed at the start of each tax year.
When to use this calculator
- When you need a fast estimate before making a bigger decision.
- When you want to compare a few scenarios using the same assumptions.
- When you need a clearer starting point before using a detailed quote or formal document.
- When you want to sanity-check a figure you have seen elsewhere before you rely on it.
- When you are preparing for a conversation with an adviser, supplier, or lender and want to arrive with realistic numbers.
A realistic South Africa planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Miles Per Year
25 years
MPG (Miles Per Gallon)
40
Fuel Price Per Litre (R)
R0.30
After entering these figures, review annual fuel cost, monthly and cost per mile together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Annual Fuel Cost
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Monthly
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Cost Per Mile
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator estimates fuel costs for a journey or over a given period based on the distance travelled, your car's fuel economy (in MPG or L/100km), and the current fuel price per litre. It applies a straightforward formula: distance divided by fuel economy gives litres consumed, which is then multiplied by the price per litre. The result does not include oil top-ups, AdBlue costs for diesel cars, or the efficiency impact of carrying heavy loads and using roof boxes. Fuel economy varies with driving conditions, so for planning purposes consider entering a figure 10–15% worse than your car's official rating to get a more realistic estimate of real-world costs.
Common mistakes
- !Using optimistic assumptions without testing a more cautious scenario as well.
- !Comparing outputs from different tools without checking that the inputs match.
- !Treating the result as a final quote instead of a planning estimate.
- !Rounding inputs too aggressively, which can produce an output that is noticeably different from your actual situation.
- !Stopping at a single run of the tool rather than adjusting the key variable up and down to understand the range of plausible outcomes.
What to do next
- Try at least one more scenario so you can compare a realistic range instead of a single estimate.
- Use the related calculators below to cross-check the decision from another angle.
- Open one of the linked guides if you need more context before you act on the result.
- Write down the key outputs from your best two or three scenarios so you have something concrete to compare when you make the final decision.
- If the result surprises you, change one input at a time to isolate which variable is driving the outcome before drawing conclusions.
Frequently asked
Use arrow keys to navigate items, Enter or Space to expand/collapse.
End-of-article next steps
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