# Kilometers to Millimeters Conversion

Enter the length in kilometers below to get the value converted to millimeters.

Results in Millimeters: 1 km = 1,000,000 mm
1 km = 100,000 cm
1 km = 1,000 m

## How to Convert Kilometers to Millimeters

To convert a kilometer measurement to a millimeter measurement, multiply the length by the conversion ratio.

Since one kilometer is equal to 1,000,000 millimeters, you can use this simple formula to convert:

millimeters = kilometers × 1,000,000

The length in millimeters is equal to the kilometers multiplied by 1,000,000.

For example, here's how to convert 5 kilometers to millimeters using the formula above.
5 km = (5 × 1,000,000) = 5,000,000 mm

### How Many Millimeters Are in a Kilometer?

There are 1,000,000 millimeters in a kilometer, which is why we use this value in the formula above.

1 km = 1,000,000 mm

Our inch fraction calculator can add kilometers and millimeters together, and it also automatically converts the results to US customary, imperial, and SI metric values.

## Kilometers

One kilometer is equal to 1,000 meters, which are defined as the distance light travels in a vacuum in a 1/299,792,458 second time interval.

The kilometer, or kilometre, is a multiple of the meter, which is the SI base unit for length. In the metric system, "kilo" is the prefix for 103. Kilometers can be abbreviated as km; for example, 1 kilometer can be written as 1 km.

## Millimeters

One millimeter is equal to one-thousandth (1/1,000) of a meter, which is defined as the distance light travels in a vacuum in a 1/299,792,458 second time interval.

The millimeter, or millimetre, is a multiple of the meter, which is the SI base unit for length. In the metric system, "milli" is the prefix for 10-3. Millimeters can be abbreviated as mm; for example, 1 millimeter can be written as 1 mm.

Millimeters are often represented by the smallest ticks on most metric rulers. To get a reference point of the size, the thickness of a US dime is 1.35mm.

We recommend using a ruler or tape measure for measuring length, which can be found at a local retailer or home center. Rulers are available in imperial, metric, or combination with both values, so make sure you get the correct type for your needs.

Need a ruler? Try our free downloadable and printable rulers, which include both imperial and metric measurements.

## Kilometer to Millimeter Conversion Table

Kilometer measurements converted to millimeters
Kilometers Millimeters
0.000001 km 1 mm
0.000002 km 2 mm
0.000003 km 3 mm
0.000004 km 4 mm
0.000005 km 5 mm
0.000006 km 6 mm
0.000007 km 7 mm
0.000008 km 8 mm
0.000009 km 9 mm
0.0000001 km 0.1 mm
0.000001 km 1 mm
0.00001 km 10 mm
0.0001 km 100 mm
0.001 km 1,000 mm
0.01 km 10,000 mm
0.1 km 100,000 mm
1 km 1,000,000 mm

## References

1. Ambler Thompson and Barry N. Taylor, Guide for the Use of the International System of Units (SI), National Institute of Standards and Technology, https://physics.nist.gov/cuu/pdf/sp811.pdf
2. United States Mint, Coin Specifications, https://www.usmint.gov/learn/coin-and-medal-programs/coin-specifications