3km

3 km, or three kilometres, is a distance equal to 3,000 metres in the metric system. It is often used in everyday contexts where precise, short-range measurements are needed, such as in urban navigation, transportation planning, and fitness tracking. In the International System of Units, a kilometre is defined as 1,000 metres, so 3 km represents a quarter of a standard marathon distance of 42.195 km.

In running and walking, a 3‑kilometre route is a common training distance for beginners and a typical distance for short road races or half‑marathon warm‑ups. Many city councils use the 3 km figure as an informal standard for the accessibility radius of public facilities, signalling that essential services lie within a manageable walking distance. Public transportation schedules also refer to 3‑km intervals to describe bus or train stops that are conveniently spaced.

The conversion to other units is straightforward: 3 km is about 1.864 miles, 3,000,000 millimetres, or 3,000,000,000 micrometres. In scientific contexts, 3 km is sometimes used to describe the range of certain atmospheric phenomena or the approximate horizontal scale of localized weather events.

In transportation, a 3‑kilometre link may refer to a short segment of road, rail, or tramway connecting two points. For example, a commuter rail line may offer a 3‑km shuttle service between a main station and a nearby industrial park. In mapping software, 3 km is often a default zoom‑level distance for local area queries.