Convert Kilometers to Millimeters

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

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1 km = 1,000,000 mm

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

More Kilometer Length Conversions

US Customary & Imperial Units
Convert to Miles
1 km is equal to 0.621371 miles
Convert to Yards
1 km is equal to 1,093.61 yards
Convert to Feet
1 km is equal to 3,280.84 feet
Convert to Inches
1 km is equal to 39,370.1 inches
SI Units
Convert to Meters
1 km is equal to 1,000 meters
Convert to Centimeters
1 km is equal to 100,000 centimeters
Convert to Micrometers
1 km is equal to 1,000,000,000 micrometers
Convert to Nanometers
1 km is equal to 1,000,000,000,000 nanometers