Example result based on the prefilled values.
Petrol Annual Cost
NZ$1,727.51
EV Annual Cost
NZ$685.71
Annual Saving
NZ$1,041.80
Continue your plan
Useful next calculations
When to use this calculator
- When you need a fast estimate before making a bigger decision.
- When you want to compare a few scenarios using the same assumptions.
- When you need a clearer starting point before using a detailed quote or formal document.
- When you want to sanity-check a figure you have seen elsewhere before you rely on it.
- When you are preparing for a conversation with an adviser, supplier, or lender and want to arrive with realistic numbers.
A realistic New Zealand planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Annual Miles
10000
Petrol Car MPG
40
Petrol Price Per Litre (NZ$)
NZ$0.30
EV Miles Per kWh
4.5 kW
After entering these figures, review petrol annual cost, ev annual cost and annual saving 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
Petrol Annual 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.
EV Annual 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.
Annual Saving
This gives you the recurring yearly benefit of the change or upgrade, which is usually the most practical starting point when comparing options. Divide it by 12 to see the monthly equivalent, or multiply by 5 to get a five-year view of the cumulative gain.
Method & assumptionsAuthoritative sources
This calculator compares the estimated annual running costs of an electric vehicle against a petrol equivalent based on your annual mileage, home electricity rate, petrol price, and the efficiency figures for each vehicle. EV efficiency is expressed in miles per kWh; petrol efficiency in MPG. The comparison covers fuel or energy costs only — it does not include purchase price differences, depreciation, insurance, or servicing, all of which vary significantly by model and driver profile. Public charging costs are not factored into the default calculation; if you rely on public chargers for a portion of your charging, adjust the electricity rate upward accordingly to reflect your blended cost per kWh.
Common mistakes
- !Using an assumption that is not supported by a current local quote, bill, statement or official source.
- !Treating a generic estimate as a lender, provider, payroll or tax authority decision.
- !Mixing monthly and annual inputs without converting them consistently.
- !Forgetting location-specific taxes, fees, eligibility rules or payroll deductions where they apply.
- !Testing only one scenario instead of checking how a cautious assumption changes the result.
What to do next
- Run a second scenario with a cautious assumption so you can see the downside clearly.
- Compare the result with the related calculators below before making a decision.
- Check current local rules, eligibility and provider terms before applying or committing money.
- Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.
- Use the result to prepare better questions for a lender, provider, adviser or employer rather than treating it as a final answer.
Frequently asked
Use arrow keys to navigate items, Enter or Space to expand/collapse.