EV Range Calculator

How to use the ev range calculator

1. Fill in the fields — they start with a worked example.
2. Read the answer, and the arithmetic shown beneath it.
3. Copy the results, or adjust the inputs to compare scenarios.

About this tool

An electric car's official range is measured on a test cycle, at a comfortable temperature, with the battery treated as fully usable. Real driving matches none of those conditions, which is why the figure on the window sticker and the figure on the dashboard disagree so often.

This calculator rebuilds the number from the parts you can actually observe. Usable capacity is smaller than the headline capacity, because manufacturers hold a buffer at each end of the pack to protect its life. Efficiency in watt-hours per mile or kilometre is the honest measure of consumption, and it is worth taking from the car's own trip computer rather than the brochure.

Cold is the largest single loss. Below freezing a battery is both less willing to give up charge and busy heating itself, and cabin heating takes energy that a combustion car gets free from waste heat. Losses of a fifth to a third in winter are ordinary, and a heat pump reduces but does not remove them. Speed matters for the same reason in the opposite direction: drag rises with the square of speed, so motorway cruising is where an EV is least efficient.

The reserve buffer is a practical rather than a technical number. Arriving at a charger with nothing left assumes the charger works, which is the assumption that strands people.

Common uses

• Estimating whether a journey is realistic without a charging stop.
• Seeing how much winter driving cuts an advertised range.
• Comparing two cars on efficiency rather than battery size alone.

Frequently asked questions

Why is my real EV range lower than the official figure?

Official figures come from a mild-temperature test cycle at moderate speeds. Cold weather, motorway speeds, heating and the pack's protective buffer all reduce what you actually get.

How much range does cold weather cost?

Commonly a fifth to a third below freezing, because the battery delivers less, heats itself, and the cabin heater draws energy a petrol car would get free from the engine.

What is a good efficiency figure?

Around 150 to 200 Wh per kilometre, or roughly 250 to 320 Wh per mile, covers most current cars. Larger and faster ones sit above that range.