leafThe honest answer is on your electricity tariff and in your driving record. Battery size tells you something about the car, but it does not tell you how much energy your Tuesday commute used or what your supplier charged for it. Start with the journey, then account for the energy that did not reach the battery.
The calculation
Estimated cost = battery energy used ÷ charging efficiency × price per kWh. Express efficiency as a fraction: 85% becomes 0.85. If starting from distance and consumption, battery energy in kWh is distance in km × Wh/km ÷ 1,000.
For example, a 60 km trip at 160 Wh/km uses 9.6 kWh at the battery. At 85% charging efficiency, replacing that energy takes an estimated 11.29 kWh from the wall. With a tariff of £0.25/kWh, the estimated energy cost is £2.82. These are illustrative inputs, not a claim about your car or a current tariff.
Try your own numbers
Why battery energy is not wall energy
Your journey log measures energy on the vehicle side. Charging involves conversion and other losses. Dividing by an efficiency assumption estimates the extra electricity required to replace the recorded energy. If you have a dependable charger or meter total, use that to check your real costs rather than treating a default percentage as a measurement.
Leaf Pro starts with an 85% charging-efficiency assumption, which you can change. Entering “15” when you mean a 15% loss is a large error: the field asks for efficiency, so that example needs “85”.
Use the tariff that applies to the session
Home, workplace and public charging can have different prices and fee structures. A cheap overnight rate does not apply automatically to a midday session. A public charger may add connection, time or parking fees. The calculator above only models the per-kWh part.
If you want a realistic household comparison, decide whether standing charges are an additional cost caused by the car or a cost you would pay anyway. Use the same accounting basis when comparing different vehicles.
Set up cost tracking in Leaf Pro
Open Settings → Electricity & charging cost and enter your price, currency and efficiency. The initial price is a placeholder, not a tariff recommendation. Journey cost figures use the recorded battery energy and your chosen assumptions. Changing those assumptions changes the estimate; it does not rewrite a past electricity bill.
Compare with petrol, diesel or LPG
For another car, calculate the fuel needed for the same distance from its real-world consumption and multiply by its fuel price. Leaf Pro keeps separate fuel profiles for petrol, diesel and LPG. That comparison concerns energy cost. Insurance, depreciation, maintenance and purchase price belong in a wider ownership budget.
Repeated recordings of your actual commute are the useful input here. Once you have them, you can stop arguing about a universal “cost per mile” and see what changes when your tariff or driving changes.