# Function: distanceKm()

```ts
function distanceKm(a, b): number;
```

Defined in: [packages/core/src/schemas/geo.ts:114](https://github.com/leifriksheim/minca/blob/main/core/src/schemas/geo.ts#L114)

The distance between two points along the Earth's surface, in kilometres (haversine)

## Parameters

| Parameter | Type |
| ------ | ------ |
| `a` | \{ `lat`: `number`; `lon`: `number`; \} |
| `a.lat` | `number` |
| `a.lon` | `number` |
| `b` | \{ `lat`: `number`; `lon`: `number`; \} |
| `b.lat` | `number` |
| `b.lon` | `number` |

## Returns

`number`