EV vs Petrol Cost Calculator — Sri Lanka

The calculator answers one question every buyer asks after import restrictions reopened: does an EV's cheaper running cost ever make up for its higher price? It compares the marginal cost of driving one kilometre in each car, scales that to your yearly mileage, and divides the price premium by the saving to find the break-even. All figures are in current rupees, with no inflation or discounting applied — stated as an assumption so the numbers stay easy to check.

1. EV cost per km. Charging is never 100% efficient, so the grid energy you pay for is higher than what reaches the battery: ev_kwh_per_km = (kWh/100km ÷ 100) × (1 + loss%). Multiply by your electricity rate (Rs/kWh) for cost per km. The default Rs 45/kWh is a CEB domestic marginal rate, approved by PUCSL.
2. Petrol/diesel cost per km. fuel_cost_per_km = price_per_litre ÷ km_per_litre. The default fuel price is the CPC gazetted retail price (Rs 434/L for petrol 92, Rs 407/L for auto diesel).
3. Saving per km and per year. Subtract the EV cost from the fuel cost for the saving per km, then multiply by annual distance: annual_saving = saving_per_km × annual_km. Optional maintenance and revenue-licence savings are added on top for the total annual saving.
4. Break-even distance and time. The premium divided by the per-km saving gives the kilometres to break even; divided by the total annual saving it gives the years: breakeven_years = price_premium ÷ total_annual_saving.
5. Cumulative check. The table adds the yearly saving up across ten years and highlights the first year it overtakes the premium — a visual confirmation of the break-even figure.

Every result is cross-checked by an independent path: instead of per-km × distance, the tool separately computes annual litres × fuel price and annual kWh × electricity rate, then subtracts. The two methods agree to the rupee, which is the "verified" note shown under the results. If your electricity rate is high or the EV is thirsty, the saving per km can turn negative — the tool then reports that the EV never pays back rather than inventing a break-even.

• Ceylon Petroleum Corporation (CPC) — gazetted retail fuel prices
• Ceylon Electricity Board (CEB) — domestic electricity tariff
• Public Utilities Commission of Sri Lanka (PUCSL) — approved tariff schedule
• Department of Motor Traffic (DMT) — revenue-licence fee schedule

Fuel price and electricity-rate defaults were last cross-checked on 2026-07-06. Both are user-editable so the tool stays correct after the next CPC price revision or CEB tariff change. This tool uses a single marginal electricity rate; for exact block-by-block charging cost see the EV Charging Cost Calculator.