How many nanometers are in 1 kilometer?

1 kilometer equals 1,000,000,000,000 nanometers, using the exact defined conversion factor rather than an estimate.

How do I convert kilometer to nanometer?

Multiply the kilometer value by 1000000000000. The converter above does this instantly to whatever precision you set.

How do I convert nanometer back to kilometer?

Use the reverse factor: 1 nanometer equals 1e-12 kilometers. You can also use the swap control in the converter above to flip the direction instantly.

Nanometer (nm) is a unit of length.

Is the kilometer to nanometer conversion exact?

Yes. Both kilometer and nanometer are defined by fixed standards rather than physical artifacts, so the factor of 1000000000000 used above is exact to as many digits as you choose to display.

Kilometers to Nanometers Converter

Q: What is a kilometer?

Kilometer (km) measures distance. A kilometer is 1,000 meters — the meter is the SI base unit of length. It is classified as a SI derived (metric prefix) unit.

About Converting Kilometers to Nanometers

Kilometer and Nanometer both measure length. Kilometer is most often used for road signage, speed limits, and vehicle odometers outside the us.

Formula

nanometers = kilometers × 1000000000000

This factor comes from each unit's defined relationship to the category's base unit: 1 kilometer equals 1000 base units, and 1 nanometer equals 1e-9 base units, so dividing one by the other gives the direct kilometer-to-nanometer factor of 1000000000000.

Simple example

1 km × 1000000000000 = 1,000,000,000,000 nm

1 kilometer = 1,000,000,000,000 nanometers.

Real-world example

10 km × 1000000000000 = 1e+13 nm

10 kilometers = 1e+13 nanometers.

Conversion table

Kilometer (km)	Nanometer (nm)
1 km	1,000,000,000,000 nm
5 km	5e+12 nm
10 km	1e+13 nm
21.0975 km	2.10975e+13 nm
42.195 km	4.2195e+13 nm
100 km	1e+14 nm

Reverse conversion: Nanometer to Kilometer

1 nm × 1e-12 = 1e-12 km

1 nanometer = 1e-12 kilometers.

kilometers = nanometers × 1e-12

For a page dedicated to this direction, see Nanometer to Kilometer.

Understanding the Kilometer

Kilometer (km) measures distance. A kilometer is 1,000 meters — the meter is the SI base unit of length. It is classified as a SI derived (metric prefix) unit.

Where it's used: Standard road, distance, and mapping unit in nearly every country except the United States

Uses of the Kilometer today

Road signage, speed limits, and vehicle odometers outside the US
Geographic and mapping distances
Endurance sports (marathons are measured in kilometers internationally, though the marathon distance itself is a fixed value in both systems)

History of the Kilometer

The meter was defined during the French Revolutionary metric reforms as one ten-millionth of the distance from the North Pole to the Equator along a meridian through Paris. 'Kilo-' is simply the SI prefix for 1,000, making the kilometer a direct decimal multiple.

The meter itself has been redefined several times as measurement precision improved — from a physical platinum-iridium bar (1889) to a krypton-86 wavelength (1960) to its current definition (1983) as the distance light travels in a fixed fraction of a second.

Historical origin. Kilometer was not the invention of a single named person; it developed through the process described above.

Understanding the Nanometer (nm)

Nanometer is 1e-9 meter units.

Kilometer — sources

BIPM — The metre (SI base unit) — Current definition and history of the meter.

Kilometers to Nanometers Converter — km to nm

Length Converter