Convert Kilometers to Millimeters

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

Results in Millimeters:

1 km = 1,000,000 mm

Do you want to convert millimeters to kilometers?

How to Convert Kilometers to Millimeters

Tape measures can be used to measure units of length, and a calculator can be used to convert to another unit

To convert a kilometer measurement to a millimeter measurement, multiply the length by the conversion ratio. One kilometer is equal to 1,000,000 millimeters, so 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

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 and millimeters are both units used to measure length. Keep reading to learn more about each unit of measure.

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.

If you need a ruler you can also download and print our free printable rulers, which include both imperial and metric measurements.

Kilometer Measurements and Equivalent Millimeter Conversions

Common kilometer values converted to the equivalent millimeter value
Kilometers	Millimeters
1 km	1,000,000 mm
2 km	2,000,000 mm
3 km	3,000,000 mm
4 km	4,000,000 mm
5 km	5,000,000 mm
6 km	6,000,000 mm
7 km	7,000,000 mm
8 km	8,000,000 mm
9 km	9,000,000 mm
10 km	10,000,000 mm
11 km	11,000,000 mm
12 km	12,000,000 mm
13 km	13,000,000 mm
14 km	14,000,000 mm
15 km	15,000,000 mm
16 km	16,000,000 mm
17 km	17,000,000 mm
18 km	18,000,000 mm
19 km	19,000,000 mm
20 km	20,000,000 mm
21 km	21,000,000 mm
22 km	22,000,000 mm
23 km	23,000,000 mm
24 km	24,000,000 mm
25 km	25,000,000 mm
26 km	26,000,000 mm
27 km	27,000,000 mm
28 km	28,000,000 mm
29 km	29,000,000 mm
30 km	30,000,000 mm
31 km	31,000,000 mm
32 km	32,000,000 mm
33 km	33,000,000 mm
34 km	34,000,000 mm
35 km	35,000,000 mm
36 km	36,000,000 mm
37 km	37,000,000 mm
38 km	38,000,000 mm
39 km	39,000,000 mm
40 km	40,000,000 mm