Energy & Sustainability
Electric Vehicle Calculators & Guides
Separate a charging session, a monthly bill, charger size, efficiency and the petrol comparison.
Start with the question you need to answer. A battery top-up needs energy and charging-power inputs; a monthly bill needs driving distance and tariffs. Charger sizing is a separate decision, and an energy-cost comparison is not a full ownership-cost comparison.
What do you want to work out?
How long will one charging session take, and what will it cost?
Inputs to gather
Usable battery capacity, starting and target charge, vehicle and charger limits, charging efficiency and the session tariff.
Energy divided by sustained charging power is a simplified time estimate, not a promise from the charger rating. Keep battery energy and billed electricity separate.
What will my monthly charging bill be?
Inputs to gather
Monthly distance, vehicle consumption, charging efficiency and home/public tariffs.
Use the cost per distance and annual result with your own driving pattern; the monthly guide shows the monthly calculation. Do not assume a fixed loss percentage.
Estimate your monthly charging costWhich home charger fits my driving and overnight window?
Inputs to gather
Daily distance, vehicle consumption, charging window, vehicle AC limit and available electrical supply.
Compare required energy with what can be delivered in your charging window. Confirm supply capacity and installation requirements with a qualified installer.
How can I compare efficiency quoted per mile and per kilometre?
Inputs to gather
The stated Wh/mi value and whether it represents battery or wall-meter energy.
Changing distance units does not account for charging losses or change the measurement boundary.
Is the EV cheaper for my journeys than petrol?
Inputs to gather
The same distance for both cars, EV consumption, charging efficiency, electricity tariff, petrol consumption and fuel price.
Compare energy cost first. Add purchase cost, depreciation, maintenance, taxes and financing separately before drawing an ownership-cost conclusion.
Separate EV energy cost from ownership costGuides behind the calculations
How to Calculate EV Charging Time and Cost
Estimate one top-up and understand the limits of a constant-power time estimate.
How Much Does It Cost to Charge an EV Per Month?
Turn distance, consumption, losses and tariffs into a monthly bill.
Electric Car vs Petrol: Running Cost Comparison
Compare the same distance and keep fuel savings separate from total ownership cost.
Convert inputs when needed
- Wh/mi → Wh/km
Compare vehicle energy use without mixing mile and kilometre denominators.
- mi → km
Put mileage and distance-based consumption on a consistent basis.
Before choosing a calculation
Does a higher charger rating guarantee a shorter session?
No. The vehicle, supply and charger limits determine available power, and actual power can change during the session. Use the session guide for time estimates and the sizing tool for an overnight charging window.
Is an EV always cheaper to run than petrol?
Compare EV energy per distance divided by charging efficiency, multiplied by the electricity price, with petrol litres per the same distance multiplied by the fuel price. The result depends on your inputs; it is not a universal saving percentage or an ownership-cost result.
Where should I get charging-loss and tariff inputs?
Use wall-meter energy and battery-energy records where available, plus the tariff you actually pay. For public charging, check the operator’s charging and session fees. Do not treat an illustrative efficiency as a property of every car.
Your next decision
Put charging alongside other household loads before changing your tariff or installation.
Use a source-specific electricity factor; a low charging bill does not establish low emissions.