Electric car vs petrol ownership cost calculator

Separate purchase price from use cost

A cheaper energy bill does not by itself recover a higher purchase price.

This comparison follows both outlays over the same ownership period, then subtracts each vehicle’s separately entered resale value. All monetary inputs must use the same currency.

The Solar self consumption and payback calculator can explore a separate home electricity scenario. Solar generation is not automatically free charging energy: account for exported electricity forgone and installation costs consistently.

Do not charge charging losses twice

Battery-side consumption is divided by charging efficiency to obtain purchased grid electricity.

If your consumption figure already measures energy at the socket, set efficiency to 100 percent. The table excludes resale until the final comparison so a paper resale assumption is not presented as cash available during ownership.

Stress test the resale assumption

Compare the vehicles first with both resale values set to zero, then restore your estimates. The change in relative ownership cost should equal the difference between the resale values. A large apparent advantage that depends mainly on resale is a different decision from an advantage supported by lower running costs.

Try a higher electricity tariff and lower annual mileage separately. Tariff changes affect energy expense, while annual mileage changes both fuel and electricity use. Financing and insurance are excluded from both sides; if those differ materially, include them in a separate cash-flow comparison before making a purchase.

Work through the entered example

At 12,000 km a year, the entered defaults give 16,000 annual EV electricity cost and 80,000 petrol cost. Across five years the EV finishes 40,000 cheaper after purchase, charger, maintenance and resale.

Start with this case, then change one input and calculate again. Keep the other assumptions fixed so the result has an interpretable cause. The result table exposes intermediate quantities and units rather than hiding them behind a single headline number.

Use the output in a real plan

Battery-side consumption is divided by charging efficiency to obtain purchased grid electricity. If your consumption figure already measures energy at the socket, set efficiency to 100 percent. The table excludes resale until the final comparison so a paper resale assumption is not presented as cash available during ownership.

Before purchasing material or comparing alternatives, check the measurements at the point where they enter the calculation. A mathematically precise answer can still be a poor plan when the measured size, loss allowance or price basis is wrong. Save the input assumptions with any result you intend to reuse.