EV Charging Cost Calculator & Gas Comparison
Estimate home and public EV charging costs, a battery charging session and annual petrol or gasoline energy costs. Account for charging losses explicitly.
Your inputs
Example inputs are hypothetical. Choose units and assumptions that match your measurements.
Your result
Enter your values, then choose Calculate.
Calculations stay in this browser. Display rounding does not change the underlying calculation.
Calculation breakdown
Method, assumptions and worked example
Estimate electricity purchased
When consumption is measured at the battery, grid kWh = battery kWh ÷ charging efficiency as a decimal. If consumption already comes from wall-meter energy, choose wall to avoid counting losses twice. Home share refers to the share of charging energy, not the number of charging visits.
Annual cost worked example
At 18 battery kWh/100 km, 90% efficiency and 12,000 km per year, grid energy is 2,400 kWh. Charging 80% at 0.20/kWh and 20% at 0.50/kWh gives an average price of 0.26/kWh and annual energy cost of 624. A petrol car using 7 L/100 km at 1.60/L costs 1,344, making the energy-cost difference 720 in the selected currency.
Cost of one charging session
A usable 60 kWh battery charged from 20% to 80% gains 36 kWh. At 90% session efficiency, it takes 40 kWh from the grid: 8 at the example home tariff or 20 at the public tariff. Session efficiency is separate because this calculation always starts with battery energy, even when annual consumption is wall-measured.
Compare like with like
Use actual tariffs including relevant per-kWh taxes. Time-of-use tariffs need an energy-weighted average. Add connection fees, subscriptions and time-based charging separately. This comparison covers energy only; purchase price, depreciation, maintenance, insurance and charger installation are excluded. It does not predict charging duration or guarantee savings.
Frequently asked questions
Why does wall energy exceed battery energy?
Some energy is lost during charging and supporting systems. Enter a measured or suitably estimated efficiency; it changes with conditions.
Does this support UK and US MPG?
Yes. Select Imperial or US MPG and use the matching gallon fuel price. Switching units clears distance and vehicle-consumption inputs to prevent accidental reinterpretation.
Can public charging be more expensive than petrol?
Yes. A negative petrol-minus-EV difference means EV energy costs more under your entered assumptions.
Method review and references
Formula and content reviewed on 10 October 2026. Worked examples are hypothetical. Methods and assumptions are explained on each page. Use actual measurements, product yields and applicable school or employment rules. These tools are independent estimates.