EV Range Calculator
Estimate real electric range after weather, speed and battery derating.
Please note: An estimate based on the figures you entered. Real-world results vary with conditions this calculation cannot see, so treat it as a starting point rather than a final answer.
What the EV Range Calculator does
Quoted EV range assumes ideal conditions. Real range depends on how much of the pack you can actually use, how much the weather costs you, and how fast you drive — and those penalties compound rather than simply adding together.
Formula
Usable pack = Capacity × Usable %Real consumption = Rated consumption × (1 + Weather penalty) × (1 + Driving penalty)Range = Available energy ÷ Real consumption × 100
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Battery capacity | kWh | Yes | Accepts more than 0. |
| Usable capacity | % | Yes | Manufacturers reserve a buffer at each end to protect the cells. |
| Rated efficiency | number | Yes | Accepts more than 0. |
| Efficiency measured in | one of 4 options | Yes | — |
| Current charge | % | Yes | — |
| Reserve you will not use | % | Optional | Charge you want left on arrival. |
| Conditions | one of 5 options | Yes | — |
| Driving style | one of 4 options | Yes | — |
How to use it
- Choose Efficiency measured in and Conditions.
- Enter Battery capacity, Usable capacity, Rated efficiency and Current charge.
- Optionally add Reserve you will not use.
- Select Calculate.
Worked example
A 75 kWh pack, 90% usable, rated 3.5 mi/kWh, full charge, 10% reserve, mild conditions and mixed driving.
- Battery
- 75 kWh
- Usable
- 90%
- Efficiency
- 3.5 mi/kWh
- Charge
- 100%
- Reserve
- 10%
Usable pack 67.5 kWh giving 236 miles at full charge. Keeping a 10% reserve leaves 212 miles available now.
Reading the result
- "Combined derate factor" is the single number capturing both weather and driving penalties multiplied together — the notes state penalties compound rather than add, so this is the honest multiplier rather than two percentages summed by hand, which would understate the real effect.
- The "how conditions change a full charge" table shows the worst realistic combination losing a dramatic share of range — useful for planning a genuine worst-case winter trip, not just the typical case.
Assumptions and limitations
- Weather and driving penalties are fixed presets — the notes say cold "commonly" costs 20–30%, meaning the chosen preset is a representative midpoint, not a guarantee for any specific vehicle or exact temperature.
- The calculation assumes one combined condition for the whole trip — a journey that shifts between city and motorway driving, or warms up along the way, experiences a blend this single-derate model can't represent.
Common mistakes
- Re-subtracting the reserve again when planning a trip — "range available now" has already accounted for it.
- Adding the weather and driving penalties instead of multiplying them — the notes and table show they compound, so simple addition understates the real range loss.
Frequently asked questions
Why is winter range so much worse?
Cold cells deliver less energy and cabin heating is a genuine electrical load. Together they commonly cost 20–30% of range near freezing.
Why is motorway range worse than city range?
Drag rises with the square of speed, and there is no braking to regenerate from. EVs are the opposite of petrol cars, which are most efficient at a steady cruise.