Convert Millimeters to Kilometers

About converting Millimeters to Kilometers

Millimeters (mm) and Kilometers (km) are both units of length, so converting between them is a single multiplication: multiply your Millimeters figure by 0.000001. Ten Millimeters comes to 0.00001 Kilometers, and a hundred works out at 0.0001 Kilometers.

Rule of thumb: going from Millimeters to Kilometers divides, so the figure always shrinks — it takes about 1,000,000 Millimeters to make a single Kilometer. If your answer came out bigger, you have the conversion the wrong way round.

What is a Millimeter?

A millimeter is one thousandth of a meter, and it is where metric measurement starts getting genuinely precise. It is the working unit of engineering drawings, machine shops, rainfall figures and camera lenses — a "50 mm lens" and "12 mm of rain overnight" are both millimeter measurements. Technical drawings in most of the world default to millimeters precisely because it lets a draughtsman specify a whole component without ever writing a decimal point.

What is a Kilometer?

A kilometer is exactly 1,000 meters — the "kilo" prefix means a thousand, as it does everywhere in the metric system. It is the unit almost every country uses for road distances and speed limits, the main exceptions being the United States and the United Kingdom, which still post miles. Its convenience is that it sits at a human scale for travel: a brisk walk covers roughly a kilometer in ten to twelve minutes, which is why city planners talk about the "fifteen-minute" neighbourhood in these terms.

To put both in perspective: a credit card is about 0.76 millimeters thick, while a kilometer is about a twelve-minute walk.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Kilometers to Millimeters converter, or browse all Length converters.