Electric driving
EV charging cost explained
Battery energy use is not always the same as electricity billed at the charger. Charging losses and tariff mix connect the two.
Convert battery consumption to wall energy
If battery consumption is 18 kWh/100km and charging efficiency is 90%, billed energy is 18 ÷ 0.90 = 20 kWh/100km. At 0.20 per kWh, energy cost is 4 per 100 km, or 0.04/km. The efficiency assumption is editable because actual losses vary.
Blend home and public tariffs
If 80% of billed charging energy costs 0.20/kWh and 20% costs 0.50/kWh, the weighted tariff is 0.26/kWh. With 20 billed kWh/100km, cost becomes 5.20 per 100 km. Use energy share, not simply the number of charging sessions, when estimating the mix.
Check your bill for additional charges
Per-minute fees, connection fees, parking penalties and subscriptions are not captured by a simple per-kWh tariff. Add charger installation to upfront cost and consider a separate allowance for recurring fixed charges. If the vehicle’s quoted efficiency already includes wall-to-battery losses, set charging efficiency to 100% to avoid counting them twice.
Method and references
Examples use nominal geometry and fixed-price scenarios, with no vehicle-specific specifications implied. See our calculation methodology and editorial policy.
Unit reference: NIST Guide to the SI: conversion factors. Financial examples are arithmetic illustrations, not market-price forecasts.