Nm to CM Converter
A centimetre is exactly 10,000,000 nanometres, so nanometres to centimetres is one division: cm = nm / 10000000, which moves the decimal point seven places to the left. That is why 100 nm is 0.00001 cm, 1,000 nm is 0.0001 cm, 10,000 nm is 0.001 cm, 5,000,000 nm is 0.5 cm and 10,000,000 nm is exactly 1 cm. Nano is the SI prefix for a billionth of a metre and centi for a hundredth, so the seven orders of magnitude between them are a definition rather than a measurement, and the division adds no error of its own. That gap is wide enough that small nanometre figures fall off the bottom of decimal display: answers print to twelve significant digits and a magnitude below 0.000001 switches to exponential notation, so 1 nm reads 1e-7 cm while 10 nm is the first whole number of nanometres that prints as a decimal, 0.000001 cm. This page opens the converter with Nanometre (nm) in the From box and Centimetre (cm) in the To box, whatever pair you converted last, and the list under the answer carries the same length in millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles.
1 nm in every length unit
Common questions
- How many cm is 1 nanometer?
- One ten-millionth of a centimetre, 0.0000001 cm, which the converter prints as 1e-7 cm because a magnitude below 0.000001 is shown in exponential notation. The pattern holds at every size: 10 nm is 0.000001 cm, 100 nm is 0.00001 cm, 500 nm is 0.00005 cm, 1,000 nm is 0.0001 cm, 10,000 nm is 0.001 cm and 1,000,000 nm is 0.1 cm. Ten million nanometres make exactly one centimetre.
- What is the formula for nm to cm?
- Centimetres = nanometres / 10,000,000, and nanometres = centimetres times 10,000,000 in the other direction, so 0.5 cm is 5,000,000 nm. Nano means 10 to the minus 9 metres and centi means 10 to the minus 2, which leaves exactly seven orders of magnitude between the two units. Because the factor is a power of ten the conversion only shifts the decimal point, seven places to the left going down to centimetres, and there is no repeating tail of the kind you get converting to inches, where 10,000,000 nm is 0.393700787402 in.
- Why does the answer read 1e-7 instead of 0.0000001?
- Because a magnitude below 0.000001 is printed in exponential notation, which beats counting zeroes: 1 nm is 1e-7 cm, 5 nm is 5e-7 cm and 0.1 nm, one angstrom, is 1e-8 cm. Above that threshold the display stays decimal, so 10 nm reads 0.000001 cm and 380 nm reads 0.000038 cm. The From box reads exponents as well as digits, so typing 2.5e7 is taken as 25,000,000 nm, and Copy result copies the headline exactly as printed, without the thousands separators.
- What is a 500 nm wavelength in centimetres?
- 0.00005 cm. Visible light runs roughly 380 to 700 nm, which is 0.000038 cm to 0.00007 cm, so the whole visible band fits inside a thousandth of a centimetre. That is why optics papers stay in nanometres or microns and only drop into centimetres when a formula demands CGS units. Type the nanometre figure in the From box and the headline is the centimetre figure, with millimetres, metres and inches listed underneath.
- Is nm to cm the same as nm to cm-1, the wavenumber?
- No, and the difference matters. A wavenumber in reciprocal centimetres is 1 divided by the wavelength in centimetres, not a scaled version of it: 500 nm is 0.00005 cm, and one over that is 20,000 cm-1. This converter scales lengths by a factor and never takes a reciprocal, so it gives you the 0.00005 cm and you do the division. The arithmetic shortcut is 10,000,000 / nm, which is why 1,000 nm is 10,000 cm-1.
- How many nanometres are in an inch?
- 25,400,000, because an inch is exactly 2.54 cm and every centimetre is 10,000,000 nm. Put 25,400,000 in the From box and the headline reads 2.54 cm, with 25.4 mm, 0.0254 m and 1 in in the list below it. The Swap units button between the two boxes reverses the pair, so this page becomes a centimetres to nanometres converter without a reload: 1 cm gives 10,000,000 nm and 2.54 cm gives 25,400,000 nm.
- Where do nanometre and centimetre sit in the list under the answer?
- Centimetre is a common length unit, so it appears in the list as well as in the headline. Nanometre never appears there, because the list leaves out the unit you are converting from. By default the list shows millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles; flip the switch in the readout, labelled Show 7 more, and it adds micrometre, thou, furlong, astronomical unit, light year and parsec. Both dropdowns list every length unit at all times, uncommon ones included, so nanometre is always selectable.
- Why does the page open on nm and cm when I last converted something else?
- Because a page that names a pair should show that pair. Arriving here sets Nanometre and Centimetre ahead of anything the converter remembered from a previous visit, and it does not overwrite that memory: open the main unit converter afterwards and it is still on the pair and category you left it on. The number in the value box does follow you between pages, since it is usually the figure you are still working on.
Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.