# List of examples of lengths

This is a list of examples of lengths, in metres in order to give an understanding of lengths.

## Shorter than 1 ym

* 1.62×10$^{−35}$ metres = 1.62×10$^{−5}$ qm = the Planck length
* 1×10$^{−30}$ metres = 1 qm = 1 quectometre, the smallest named subdivision of the metre in the SI base unit of length.
* 1×10$^{−27}$ metres = 1 rm = 1 rontometre = 1000 quectometres

## 1 ym to 1 zm

* 1×10$^{−24}$ metres = 1 ym = 1 yoctometre = 1000 rontometres
* 1×10$^{−23}$ metres = 10 ym
* 2×10$^{−23}$ metres = 20 ym, the effective cross-section radius of 1 MeV neutrinos as measured by Clyde Cowan and Frederick Reines
* 1×10$^{−22}$ metres = 100 ym

## 1 zm to 1 am

* 1×10$^{−21}$ metres = 1 zm = 1 zeptometre = 1000 yoctometres
* 2×10$^{−21}$ metres = radius of effective cross section for a 20 GeV neutrino scattering off a nucleon
* 7×10$^{−21}$ metres = radius of effective cross section for a 250 GeV neutrino scattering off a nucleon
* 1×10$^{−20}$ metres = 10 zm
* 1×10$^{−19}$ metres = 100 zm
* 310 zm — de Broglie wavelength of protons at the Large Hadron Collider (4 TeV as of 2012)

## 1 am to 1 fm

* 1×10$^{−18}$ metres = 1 am = 1 attometre = 1000 zeptometres
* 1 am — sensitivity of the LIGO detector for gravitational waves
* 1×10$^{−17}$ metres = 10 am
* 1×10$^{−16}$ metres = 100 am
* 0.85 fm — approximate proton radius

## 1 fm to 1 pm

* 1×10$^{−15}$ metres = 1 fm = 1 femtometre = 1000 attometres
* 1.5 fm — diameter of the Scattering Cross Section of an 11 MeV proton with a target proton
* 2.81794 fm — classical electron radius
* 7 fm - the radius of the effective scattering cross section for a gold nucleus scattering a 6 MeV alpha particle over 140 degrees
* 1×10$^{−14}$ metres = 10 fm
* 1×10$^{−13}$ metres = 100 fm
* 1×10$^{−12}$ metres = 1 pm = 1 picometre = 1000 femtometres

## 1 picometre

Lengths between 10$^{−12}$ and 10$^{−11}$ m (1 and 10 pm).
* 1 pm = 1 picometre = 1000 femtometres
* 1 pm = distance between atomic nuclei in a white dwarf star
* 2.4 pm — The Compton wavelength of the electron.
* 5 pm — shorter X-ray wavelengths (approx.)

## 10 picometres

Lengths between 10$^{−11}$ and 10$^{−10}$ m (10 pm and 100 pm).
* 25 pm — empirical radius of hydrogen atom
* 28 pm — covalent radius of helium atom
* 31 pm — covalent radius of hydrogen atom
* 31 pm — calculated radius of helium atom
* ~50 pm — best resolution of a high-resolution transmission electron microscope
* 53 pm — calculated radius of hydrogen atom

## 100 picometres

Lengths between 10$^{−10}$ and 10$^{−9}$ m (100 pm and 1 nm).
* 100 pm — 1 angstrom
* 100 pm — covalent radius of sulfur atom
* 120 pm — van der Waals radius of a neutral hydrogen atom
* 126 pm — covalent radius of ruthenium atom
* 135 pm — covalent radius of technetium atom
* 153 pm — covalent radius of silver atom
* 154 pm — mode length of (C-C) covalent bond
* 155 pm — covalent radius of zirconium atom
* 175 pm — covalent radius of thulium atom
* 200 pm — highest resolution of a typical electron microscope
* 225 pm — covalent radius of caesium atom
* 340 pm — thickness of single layer graphene
* 356.68 pm — width of diamond cell (unit cell)
* 403 pm — width of lithium fluoride cell
* 500 pm — width of α helix protein
* 560 pm — width of sodium chloride cell
* 700 pm — width of glucose molecule
* 780 pm — mean width of quartz cell
* 820 pm — mean width of ice cell
* 900 pm — mean width of coesite cell
* 900 pm — width of sucrose molecule

## 10 nanometres 1x10$^{−9}$m

To help compare different orders of magnitude this page lists lengths between 10$^{−8}$ and 10$^{−7}$ m (10 and 100 nm).
* 10 nm = 10 nanometres = 10$^{−8}$ metres
* 10 nm — lower size of tobacco smoke
* 10 nm Shortest extreme ultraviolet wavelength or longest X-ray wavelength
* 11 nm — the average half-pitch of a memory cell speculated to be manufactured in 2015.
* 16 nm — technology is projected to be reached by semiconductor companies in the 2013 timeframe
* 18 nm — diameter of tobacco mosaic virus (Generally, viruses range in size from 20 nm to 450 nm.)
* 20 nm — width of bacterial flagellum
* 20 nm to 80 nm — thickness of cell wall in Gram-positive bacteria
* 22 nm — Smallest feature size of production microprocessors in September 2009
* 22 nm — the average half-pitch of a memory cell expected to be manufactured at around the 2011–2011 time frame.
* 30 nm — lower size of cooking oil smoke
* 32 nm — the average half-pitch of a memory cell manufactured at around the 2009–2010 time frame.
* 45 nm — the average half-pitch of a memory cell manufactured at around the 2007–2008 time frame.
* 50 nm — upper size for airborne virus particles
* 50 nm — flying height of the head of a hard disk
* 65 nm — the average half-pitch of a memory cell manufactured at around the 2005–2006 time frame.
* 90 nm — the average half-pitch of a memory cell manufactured at around the 2002–2003 time frame.
* 100 nm — larger than 90% of the particles of wood smoke (ranges from 7 to 3000 nanometres)

## 100 nanometres

Lengths between 10$^{−7}$ and 10$^{−6}$ m (100 nm and 1 μm).
* 100 nm — greatest particle size that can fit through a surgical mask
* 100 nm — 90% of particles in wood smoke are smaller than this.
* 120 nm — greatest particle size that can fit through a ULPA filter
* 120 nm — diameter of a human immunodeficiency virus (HIV)
* 125 nm — standard depth of pits on compact discs (width: 500 nm, length: 850 nm to 3.5 μm)
* 180 nm — typical length of the rabies virus
* 200 nm — typical size of a Mycoplasma bacterium, among the smallest bacteria
* 300-400 nm — near ultraviolet wavelength
* 300 nm — greatest particle size that can fit through a HEPA (high efficiency particulate air) filter (N100 removes up to 99.97% at 0.3 micrometres, N95 removes up to 95% at 0.3 micrometres)
* 400–420 nm — wavelength of violet light
* 420–440 nm — wavelength of indigo light
* 440–500 nm — wavelength of blue light
* 500–520 nm — wavelength of cyan light
* 520–565 nm — wavelength of green light
* 565–590 nm — wavelength of yellow light
* 590–625 nm — wavelength of orange light
* 625–700 nm — wavelength of red light
* 700–1400 nm — wavelength of near-infrared radiation

## 1 micrometre

To help compare different orders of magnitude this page lists some items with lengths between 10$^{−6}$ and 10$^{−5}$ m (between 1 and 10 micrometres, or μm).
* ~0.7–300 μm — Wavelength of infrared radiation
* 1 μm — the side of square of area 10$^{−12}$ m$^2$
* 1 μm — edge of cube of volume 10$^{−18}$ m$^3$ (one femtolitre)
* 1–10 μm — diameter of a typical bacterium
* 1.55 μm — wavelength of light used in optical fibre
* 3–4 μm — size of a typical yeast cell
* 5 μm — length of a typical human spermatozoon's head
* 6 μm — anthrax spore
* 7 μm — diameter of the nucleus of a typical eukaryotic cell
* about 7 μm — diameter of human red blood cells
* 3–8 μm — width of strand of spider web silk
* 8 μm — width of a chloroplast
* 9 μm — thickness of the tape in a 120-minute compact cassette.
* about 10 μm — size of a fog, mist or cloud water droplet

## 10 micrometres

To help compare different orders of magnitude, this page lists lengths between 10$^{−5}$ and 10$^{−4}$ m (10 μm and 100 μm).
* 10 μm — width of cotton fibre
* 10 μm — transistor width of the Intel 4004, the world's first commercial microprocessor
* 10 μm — mean longest dimension of a human red blood cell
* 5–20 μm — dust mite excreta
* 10.6 μm — wavelength of light emitted by a carbon dioxide laser
* 15 μm — width of silk fibre
* 16 μm — diameter of a micromirror in a typical Digital micromirror device
* 17 μm — length of a tobacco mosaic virus
* 17 μm — minimum width of a strand of human hair
* 17.6 μm — one twip, a unit of length in typography
* 10 to 55 μm — width of wool fibre
* 25.4 μm — 1/1000 inch, commonly referred to as 1 mil in the U.S. and 1 thou in the UK
* 30–50 μm — diameter of a minicolumn in the human cortex
* 50 μm — typical length of Euglena gracilis, a flagellate protist
* 50 μm — typical length of a human liver cell, an average-sized body cell
* 78 μm — width of a pixel on the display of the iPhone 4, marketed as Retina Display
* 90 μm — paper thickness in average
* 1 myriometre, Distances shorter than 100 μm

## 100 micrometres

To help compare different orders of magnitude, this page lists lengths between 10$^{−4}$ and 10$^{−3}$ m (100 μm and 1 mm).
* 100 μm – 1/10 of a millimetre
* 100 μm – 0.00394 inches
* 100 μm – average diameter of a strand of human hair
* 100 μm – thickness of a coat of paint
* 100 μm – length of a dust particle
* 120 μm – diameter of a human ovum
* 170 μm – length of the largest mammalian sperm cell (rat)
* 181 μm – maximum width of a strand of human hair
* 100–400 μm – length of Demodex mites living in human hair follicles
* 200 μm – typical length of Paramecium caudatum, a ciliate protist
* 250–300 μm – length of a dust mite
* 340 μm – length of a single pixel on a 17-inch monitor with a resolution of 1024×768
* 500 μm – typical length of Amoeba proteus, an amoeboid protist
* 500 μm – MEMS micro-engine
* 560 μm - thickness of the central area of a human cornea
* 760 μm – thickness of a credit card

## 1 millimeter

To help compare different orders of magnitude this page lists lengths between 10$^{−3}$ and 10$^{−2}$ m (1 mm and 1 cm).
* 1.0 mm — ⁠1/1000⁠ of a metre
* 1.0 mm — 0.03937 inches or 5⁄127 (exactly)
* 1.0 mm — side of square of area 1 mm$^2$
* 1.0 mm — diameter of a pinhead
* 1.5 mm — length of average flea
* 2.54 mm — distance between pins on old DIP (dual-inline-package) electronic components
* 5 mm — length of average red ant
* 5.56×45mm NATO — standard ammunition size
* 7.62×51mm NATO — common military ammunition size

## 1 centimeter

Lengths between 10$^{−2}$ and 10$^{−1}$ m (1 and 10 cm).
* 1 cm — 10 millimetres
* 1 cm — 0.39 inches
* 1 cm — edge of square of area 1 cm$^2$
* 1 cm — edge of cube of volume 1 ml
* 1 cm — approximate width of average fingernail
* 1.5 cm — length of a very large mosquito
* 2 cm — approximate width of an adult human finger
* 2.54 cm — 1 inch
* 3.1 cm — 1 attoparsec (10$^{−18}$ parsecs)
* 3.5 cm — width of film commonly used in motion pictures and still photography
* 4.3 cm — minimum diameter of a golf ball
* 7.3-7.5 cm — diameter of a baseball
* 8.6 cm × 5.4 cm — dimensions of a typical credit card

## 1 decimetre

Lengths between 10 and 100 centimetres (10$^{−1}$ and 1 metre).

### Conversions

10 centimetres (abbreviated to 10 cm) is equal to
* 1 decimetre (dm), a term not in common use
* 100 millimetres
* 3.9 inches
* A side of a square of area 0.01 m$^2$
* The edge of a cube with a volume of 1×10$^{−3}$ m$^3$ (one litre)

### Wavelengths

* 10 cm = 1.0 dm – wavelength of the highest UHF radio frequency, 3 GHz
* 12 cm = 1.2 dm – wavelength of the 2.45 GHz ISM radio band
* 21 cm = 2.1 dm – wavelength of the 1.4 GHz hydrogen emission line, a hyperfine transition of the hydrogen atom
* 100 cm = 10 dm – wavelength of the lowest UHF radio frequency, 300 MHz

### Human-defined scales and structures

* 10.16 cm = 1.016 dm — 1 hand used in measuring height of horses (4 inches)
* 12 cm = 1.2 dm — diameter of a Compact Disc (CD) (= 120 mm)
* 15 cm = 1.5 dm — length of a Bic pen with cap on
* 22 cm = 2.2 dm — diameter of a typical soccer ball
* 30.48 cm = 3.048 dm — 1 foot
* 30 cm = 3 dm — typical school-use ruler length (= 300 mm)
* 60 cm = 6 dm — standard depth (front to back) of a domestic kitchen worktop in Europe (= 600 mm)
* 90 cm = 9 dm — average length of a rapier, a fencing sword
* 91.44 cm = 9.144 dm — one yard
* Cigarettes 100 mm (4 in) in length

### Nature

* 10 cm = 1 dm — diameter of the human cervix upon entering the second stage of labour
* 15 cm = 1.5 dm — approximate size of largest beetle species
* 29 cm = 2.9 dm — length of average human foot
* 29.98 cm = distance light travels in one nanosecond
* 31 cm = 3.1 dm — wingspan of largest butterfly species Ornithoptera alexandrae
* 56 cm = 5.6 dm — the length of the average erect horse pеnis
* 50 to 65 cm — a pizote's tail
* 66 cm — length of the longest pine cones (produced by the sugar pine)

## Longer

* 1 metre
* 1 decametre
* 1 hectometre
* 1 kilometre
* 1 myriametre
* 100 kilometres
* 1 megametre
* 10 megametres
* 100 megametres

## 1 gigametre

Lengths starting at 10$^9$ metres (1 gigametre (Gm) or 1 million kilometres).
Distances shorter than 10$^9$ metres
* 1.4 Gm — Diameter of Sun
* 1.5 Gm — (proposed) Expected orbit from Earth of the James Webb Space Telescope
* 2.19 Gm — Closest approach of Comet Lexell to Earth, happened on 1 July 1770; closest comet approach on record
* 3 Gm — Total length of "wiring" in the human brain.
* 4.2 Gm — Diameter of Algol B
* 5.0 Gm — Closest approach of Comet Halley to Earth, happened on 10 April 837
* 5.0 Gm — (proposed) Size of the arms of the giant triangle shaped Michelson interferometer of the Laser Interferometer Space Antenna (LISA) planned to start observations in or around 2015.
* 7.9 Gm — Diameter of Gamma Orionis
* 9.0 Gm — Estimated diameter of the event horizon of Sagittarius A*, the supermassive black hole in the center of the Milky Way galaxy

## Longer

* 10 gigametres
* 100 gigametres
* 1 terametre
* 10 terametres
* 100 terametres
* 1 light year
* 1 petametre
* 10 petametres
* 100 petametres
* 1 exametre
* 10 exametres
* 100 exametres
* 1 zettametre
* 10 zettametres
* 100 zettametres
* 1 yottametre
* 10 yottametres
* 100 yottametres
* 1 ronnametre
* 10 ronnametres
* 100 ronnametres
* 1 quettametre
* 10 quettametres
* 100 quettametres