# EV Range and Efficiency Calculator

> Converts an electric vehicle's energy consumption between Wh/km, kWh/100 km, Wh/mile, mi/kWh and km/kWh, computes the driving range from the battery capacity and usable share, and reports the EPA MPGe equivalent (33.7 kWh per US gallon of gasoline).

- Calculator id: `ev-range-efficiency` · Category: Home Energy & Electrical (`energy`) · Tool name: `calculate_ev_range_and_efficiency`
- Canonical page: https://tttkmbb.com/energy/ev-range-efficiency · This document: https://tttkmbb.com/energy/ev-range-efficiency.md · JSON definition: https://tttkmbb.com/energy/ev-range-efficiency.json

## Purpose

Converts an electric vehicle's energy consumption between Wh/km, kWh/100 km, Wh/mile, mi/kWh and km/kWh, computes the driving range from the battery capacity and usable share, and reports the EPA MPGe equivalent (33.7 kWh per US gallon of gasoline).

**Use when:** You want an EV's range for a given consumption, or need to compare efficiency figures quoted in different units (European kWh/100 km, US mi/kWh or MPGe).

**Do not use when:** You need charging time (use ev-charging-time) or running-cost comparison with a petrol car (use fuel-vs-ev-cost); real-world consumption varies with speed, temperature and heating by ±30 % or more.

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `battery_capacity_kwh` | number | kWh | required | Battery capacity in kilowatt-hours (usable capacity if known; otherwise use usable_percent). (> 0, max 1000) |
| `efficiency_value` | number |  | required | Energy consumption or efficiency figure in the unit given by efficiency_unit (e.g. 160 Wh/km, 16 kWh/100 km, 3.9 mi/kWh). (> 0, max 100000) |
| `efficiency_unit` | enum: wh_per_km \| kwh_per_100km \| wh_per_mile \| mi_per_kwh \| km_per_kwh |  | required | Unit of efficiency_value. |
| `usable_percent` | number | % | optional, default 100 | Share of the battery available for driving (e.g. 90–95 % when the nominal capacity includes a buffer, or 60 for a 20–80 % daily window). (min 1, max 100) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `usable_energy_kwh` | number | kWh | battery_capacity_kwh × usable_percent / 100. |
| `range_km` | number | km | Usable energy / consumption. |
| `range_miles` | number | mi | range_km / 1.609344. |
| `wh_per_km` | number | Wh/km | Consumption converted to watt-hours per kilometre. |
| `kwh_per_100km` | number | kWh/100 km | wh_per_km / 10. |
| `wh_per_mile` | number | Wh/mi | wh_per_km × 1.609344. |
| `mi_per_kwh` | number | mi/kWh | 1000 / wh_per_mile. |
| `km_per_kwh` | number | km/kWh | 1000 / wh_per_km. |
| `mpge` | number | MPGe | mi_per_kwh × 33.7 (EPA miles per gallon gasoline-equivalent). |

## Formula

`wh_per_km = efficiency_value converted (kWh/100 km × 10; Wh/mile / 1.609344; 1000 / (mi/kWh × 1.609344); 1000 / (km/kWh)); usable_energy_kwh = battery_capacity_kwh × usable_percent / 100; range_km = usable_energy_kwh × 1000 / wh_per_km; range_miles = range_km / 1.609344; kwh_per_100km = wh_per_km / 10; wh_per_mile = wh_per_km × 1.609344; mi_per_kwh = 1000 / wh_per_mile; km_per_kwh = 1000 / wh_per_km; mpge = mi_per_kwh × 33.7`

Pure unit arithmetic; the EPA defines MPGe with 33.7 kWh as the energy content of one US gallon of gasoline (115,000 BTU). Official WLTP/EPA consumption figures already include charging losses, while dashboard figures usually do not.

## Data Sources

- U.S. EPA fueleconomy.gov – Electric vehicle label (MPGe, 33.7 kWh per gallon) — https://www.fueleconomy.gov/feg/label/learn-more-electric-label.shtml (government, retrieved 2026-09-24)
- Wikipedia – Miles per gallon gasoline equivalent — https://en.wikipedia.org/wiki/Miles_per_gallon_gasoline_equivalent (reference, retrieved 2026-09-24)
- U.S. DOE Alternative Fuels Data Center – Charging Electric Vehicles at Home — https://afdc.energy.gov/fuels/electricity-charging-home (government, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/ev-range-efficiency?battery_capacity_kwh=…&efficiency_value=…&efficiency_unit=…`
- `POST https://tttkmbb.com/api/v1/calculate/ev-range-efficiency` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/ev-range-efficiency · OpenAPI operationId `calculate_ev_range_and_efficiency` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "ev-range-efficiency", "inputs": {…}}`

## Example

- 75 kWh at 160 Wh/km: inputs `{"battery_capacity_kwh":75,"efficiency_value":160,"efficiency_unit":"wh_per_km"}` → `{"range_km":468.8,"range_miles":291.3,"kwh_per_100km":16,"wh_per_mile":257.5,"mi_per_kwh":3.884,"km_per_kwh":6.25,"mpge":130.9}`
- 60 kWh at 4 mi/kWh, 90 % usable: inputs `{"battery_capacity_kwh":60,"efficiency_value":4,"efficiency_unit":"mi_per_kwh","usable_percent":90}` → `{"usable_energy_kwh":54,"range_miles":216,"range_km":347.6,"wh_per_km":155.3,"kwh_per_100km":15.53,"mpge":134.8}`

```
GET https://tttkmbb.com/api/v1/calculate/ev-range-efficiency?battery_capacity_kwh=75&efficiency_value=160&efficiency_unit=wh_per_km
```

## Limitations

You need charging time (use ev-charging-time) or running-cost comparison with a petrol car (use fuel-vs-ev-cost); real-world consumption varies with speed, temperature and heating by ±30 % or more. Pure unit arithmetic; the EPA defines MPGe with 33.7 kWh as the energy content of one US gallon of gasoline (115,000 BTU). Official WLTP/EPA consumption figures already include charging losses, while dashboard figures usually do not. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**What is MPGe?**

Miles per gallon gasoline-equivalent: the miles an EV travels on 33.7 kWh, the energy in one US gallon of gasoline. It compares energy efficiency, not cost or emissions.

**Why is my real range lower than this?**

Rated consumption comes from standard test cycles; motorway speed, cold weather, cabin heating and roof loads raise consumption by 20–50 %, and most drivers keep a 10–20 % reserve.

**Is battery capacity gross or net?**

Manufacturers quote gross (nominal) or net (usable) capacity. Enter the usable value with usable_percent = 100, or the gross value with the usable share (typically 90–96 %).

## Related

- [EV Charging Time Calculator](https://tttkmbb.com/energy/ev-charging-time.md) — Time and cost to add the energy for this range.
- [Fuel vs EV Cost Calculator](https://tttkmbb.com/energy/fuel-vs-ev-cost.md) — Running cost versus a petrol or diesel car.
- [Fuel Economy Converter](https://tttkmbb.com/conversion/fuel-economy.md) — Convert the combustion-car figures (mpg, L/100 km, km/L).