Electricity is only one line in the budget
An EV-versus-petrol comparison should use the same ownership period and annual distance. Include purchase and eventual resale values, energy, road tax, insurance, servicing, tyres and any financing. Lower energy spend does not automatically mean lower total ownership cost.
Estimate charging spend
Annual driving energy is approximately annual kilometres × consumption in kWh/100 km ÷ 100. Electricity billed by a charger can be higher than energy used for driving because charging has losses. Use your actual billed energy where possible.
Use realistic inputs
As a simple illustration, 20,000 km at 18 kWh/100 km is 3,600 kWh of driving energy. At an assumed S$0.70/kWh that is S$2,520 before charging losses, parking or other fees. These figures demonstrate the calculation; they are not a forecast or a current charging tariff.
Build a complete comparison
- Purchase price minus expected resale value over your ownership period.
- Charging or petrol costs using your own driving distance.
- Road tax and insurance quotes for each exact model.
- Servicing, tyres, repairs and warranty exclusions.
- Charging-related parking and any home-installation cost.
Avoid false precision
Resale values and repair costs are uncertain. Compare a range of outcomes rather than treating a single estimate as guaranteed.
Reduce the cost of each charging stop →EV cost of ownership: questions to compare
Is an EV always cheaper to own than a petrol car?
The result depends on the exact vehicles, purchase prices, annual distance, charging access, insurance, taxes and resale assumptions. Compare a whole ownership period using the same inputs rather than relying only on fuel-versus-electricity savings.
Where can I check EV road tax and insurance costs?
Use the EV road-tax guide to find the official calculation, and obtain like-for-like EV insurance quotations. Check whether quoted figures are annual and what coverage or excess each quote includes.
Compare an EV and petrol car on the same basis
Use your intended ownership period rather than comparing one month of charging with a full year of petrol. Treat purchase price minus eventual resale value as depreciation; do not add both full purchase price and depreciation to the same total. Include quoted road tax, insurance, servicing, tyres and charging-related parking. Keep borrowing costs separate if you are comparing cash purchases.
The calculator below accepts your assumptions. Test a higher charging tariff and a lower resale value as well as your central case. A favourable energy result alone cannot establish which car is cheaper to own.