How the calculation works
We start with a base range, then knock it down with realistic factors for temperature, driving style and cabin heating:
- Base range = usable battery (kWh) x efficiency (miles per kWh)
- Realistic range = base range x temperature factor x driving factor x heating factor
If you enter an official WLTP range instead of efficiency, we work the efficiency out for you by dividing the WLTP range by your usable battery size, then apply the same factors.
Why UK winters cut your range
Cold weather is the single biggest hit to EV range, and it stacks up from a few causes:
- Battery chemistry slows in the cold, so the pack cannot deliver or accept energy as freely
- Cabin heating draws real power, unlike a petrol car that heats the cabin with waste engine heat
- Cold, denser air and wet roads add rolling and aerodynamic resistance
The temperature factors built in reflect this: a mild 10C day costs you around 8%, a cold 2C day around 20%, and a freezing sub-zero day around 30%, before heating. Turn the cabin heater on in the cold and we knock off a further 8%.
How driving style changes range
Speed matters more than almost anything else. Air resistance rises sharply with speed, so a steady motorway run at 70mph uses far more energy than gentle town driving:
- Gentle, urban driving can beat the official figure, so we add about 10%
- Mixed driving sits at the baseline
- Motorway at 70mph typically costs around 18%
This is why your range looks great around town and drops on a long motorway trip, even in summer.
Assumptions and accuracy
Estimates use temperature, driving-style and heating factors tuned for typical UK conditions. Real range varies with your specific car, route, tyres, load and driving. Figures are a guide, not a guarantee.
These figures are estimates, not a guarantee. Last updated 2026-06-11.