Benchmark quantities

Benchmark Values for (Nearly) Any Type of Physical Quantity

When encountering the unfamiliar in terms of the very large or the very small, this page is meant to help put the unfamiliar into perspective. For example, people know that a million miles (or kilometers) is a very long distance. But what is it comparable to? You probably know that it's larger than a typical continent ... or than Earth itself. But is it comparable to the distance to the Moon, or perhaps to the Sun? Or to the nearest star other than the Sun? Or to the size of our galaxy ... or the distance to the nearest galaxy?

Likewise, one millionth of an inch (or of a centimeter) is certainly small, but is it most comparable to the size of an atomic nucleus, a whole atom, a virus, or perhaps a single-celled organism?

Besides distances, similar questions can be asked about very fast or very slow speeds, very large or small masses, or time spans, or temperatures, ... and many other types of physical quantities.

Every quantity is given in terms of S.I. (metric) units. In some cases, alternative units are given if they are in common use. For example, the distance between Earth and the Sun, besides being given in meters, is also one Astronomical Unit (AU) by definition, and the AU is used for the distances to other objects within the solar system as well. Still larger distances are well represented by using light-years.

Density

There is a limit to how closely atoms can be packed together under normal conditions, so there is a limit to how high a normal material density can be. To achieve higher densities then requires special conditions, for example those found in the core of a star, or inside an atomic nucleus or neutron star.

Value, in kilograms per cubic meter	Alternative Units	Description
2.2 x 10-27		Dark matter, average for universe
4-5 x 10-22		Dark matter, near solar system
6 x 10-22		Dark matter, in Milky Way halo
1 x 10-12		Air, ultra-high vacuum conditions (10-9 mbar or 10-12 atm)
0.18		Helium, 20 C and atmospheric pressure
1.2		Air, 20 C and atmospheric pressure
9.0		Compressed air, 20 C, 96 psig (111 psia or 7.5 atm abs.)
250	0.25 g/cc	Balsa wood
534	0.534 g/cc	Lithium, the lowest-density solid element
1000	1 g/cc	Water
1400	1.4 g/cc	Sun (average)
2200-3400	2.2-3.4 g/cc	Typical rocks
2700	2.7 g/cc	Aluminum
5500	5.5 g/cc	Earth (average)
8000, 9000	8, 9 g/cc	Steel, copper
11,400	11.4 g/cc	Lead
12,000	12 g/cc	Earth's core
22,600	22.6 g/cc	Osmium, the densest element
160,000	160 g/cc	The sun's core (est.)
~1 x 1017		Neutron star or atomic nucleus

Dimensionless values

A dimensionless value or quantity has no associated units such as meters or kilograms. It is simply a pure number. Examples include the fraction of air molecules that are oxygen (0.21 or 21%), the number pi (3.1415...), and Avogadro's number (6.02 x 10²³.

Loosely speaking, numbers can be classified as either very small compared to the number 1, very large compared to 1, or comparable to 1. For small numbers, alternate units can be given in terms of percent (%) or parts per million (ppm).

Value	Alternative Units	Description
Composition of air
0.0004	0.04%, 400 ppm	Fraction of air molecules that are carbon dioxide (0% humidity)
0.009	0.9%	Fraction of air molecules that are argon (0% humidity)
0.006, 0.023, 0.073	0.6%, 2.3%, 7.3%	Fraction of air molecules that are water vapor at 100% humidity and temperatures of 0, 20, 40 C (32, 68, 104 F), respectively
0.21	21%	Fraction of air molecules that are oxygen (0% humidity)
0.78	78%	Fraction of air molecules that are nitrogen (0% humidity)
0.25-0.3	25-30%	Efficiency of a typical thermodynamic heat engine
1	100%	One. Unity. The multiplicative identity.
3 (approx.)		The numbers pi (3.14159...) and e (2.71828...)
3		The number of quarks in a proton or neutron
8		The number of planets in the solar system
22-23		The number of revolutions the Sun has made around the galaxy
208		The number of protons and neutrons, combined, in a nucleus of lead-208, the heaviest stable atomic nucleus
3.7 x 107	37 million	Population of Tokyo (2018), the most populous city in the world
3.1 x 108	310 million	Population of the USA (2010 census)
1-4 x 109	1-4 billion	Estimated number of stars in the Milky Way galaxy
7 x 109	7 billion	Population of the world (2010)
6 x 1023	1 mole	Avogadro's number The number of hydrogen atoms in 1 gram, or the number of carbon-12 atoms in 12 grams
7.9 x 1024	13 moles	The number of molecules in 8 fluid ounces of water

Distance, length, height

Value, in meters	Alternative Units	Description
1.62 x 10-35		Planck length
1.8 x 10-15		Diameter of a proton (hydrogen nucleus)
1-1.2 x 10-14	10-12 fm	Diameter of nucleus for heavy atoms
5.29 x 10-10	0.529 Angstroms	Radius of hydrogen atom (Bohr model)
3 x 10-8	30 nm	rhinovirus (cold virus) diameter
0.8-1.2 x 10-7	80-120 nm	Influenza virus diameter
0.2-3 x 10-7	20-300 nm	Virus diameter (typical range)
4-7 x 10-7	400-700 nm	Wavelength range of visible light
0.1-600 x 10-6		Bacterium
1-2 x 10-5	0.01-0.02 mm, 0.0004-0.0008 inches	Amoeba (typical)
1 x 10-4	0.1 mm, 0.004 or 1/250 inch	Human hair thickness (typical)
6-7 x 10-3	6-7 mm, 1/4 inch	Housefly length (typical)
1.5-1.8	5-6 feet	Human height (typical)
25	82 feet	Blue whale length
527	1729 feet	Sears Tower height (to top of antenna)
8800	29,000 feet, 5.5 miles	Mount Everest, height above sea level
4 x 106	4000 km, 2500 miles	North America, width at approx. 40 degrees North latitude; Los Angeles-to-New York distance
1.3 x 107	13,000 km, 7900 miles	Earth's diameter
3.0 x 108	190,000 miles	One light-second, the distance that light travels in one second
3.8 x 108	240,000 miles	Earth-Moon distance
1.4 x 109	870,000 miles	The Sun's diameter
1.50 x 1011	1 Astronomical Unit (AU) 93 million miles	Earth-Sun average distance
4.5 x 1012	30 AU	Sun-Neptune distance
9.46 x 1015	1 light-year 63.2 thousand AU	The distance that light travels in one year
3.09 x 1016	3.26 light years	1 parsec
4.0 x 1016	4.2 ly	Sun-Proxima Centauri distance
8.6 x 1017	91 light years	Geometric mean of distances to 20 brightest stars, excluding the Sun (One measure of a "typical" distance to the brighter stars in the sky)
3.2 x 1018	340 light years	Mean of distances to 20 brightest stars, excluding the Sun (Another measure of a "typical" distance to the brighter stars in the sky)
9.5 x 1020	100,000 light years	Diameter of our galaxy, the Milky Way
1.5 x 1021	160,000 light years	Distance to Large Magellanic Cloud
2.4 x 1022	2,500,000 light years	Distance to Andromeda galaxy

Energy

Value, in joules	Alternative Units	Description
9.4 x 10-25	5.9 x 10-6 eV	Hyperfine energy difference in the ground state of a hydrogen atom
6.1 x 10-21	0.038 eV	Energy of cesium-133 hyperfine transition used to define the second
1.60 x 10-19	1 eV	One electronvolt
2.8 x 10-19	1.8 eV	Low energy of visible-light photon (red, 700 nm wavelength)
5.0 x 10-19	3.1 eV	High energy of visible-light photon (violet, 400 nm wavelength)
2.2 x 10-18	13.6 eV	Energy to ionize a hydrogen atom
8.2 x 10-14	0.5110 MeV	Electron rest-mass energy
1.5 x 10-10	938.3 MeV	Proton rest-mass energy
5 x 10-5		Kinetic energy of housefly flying (12 mg, 3 m/s)
4.2	1 calorie (with lowercase "c")	One calorie, or the energy needed to raise the temperature of 1 gram of water by 1 C.
70		Kinetic energy of human walking (80 kg, 1.3 m/s or 3 mph)
1055	1 BTU	One British thermal unit
2400		Kinetic energy of 0.22 caliber long-rifle bullet (40 g, 346 m/s)
4200	1 Calorie (with uppercase "C") or 1000 calories (with lowercase "c")	One "food Calorie", or the energy needed to raise the temperature of 1 kilogram of water by 1 C.
4300		Kinetic energy of human world-class sprinter (80 kg, 10.4 m/s)
11,000	0.003 kW-h	Electrical energy in a battery: AA cell (1.5 volts, 2000 mA-hours)
1.0 x 105		Energy to heat 10 oz. (280 g) of water from 20 C to 100 C (68 F to 212 F)
6.7 x 105		Energy to boil 10 oz. (280 g) of water
3.6 x 106	1 kW-h	One kilowatt-hour A good example benchmark to answer the question: How small is one joule of energy? Answer: A kilowatt-hour of electricity typically costs around 10 cents (ballpark value). A joule of electricity then costs less than one-millionth of that. So a joule is a really small amount of energy.
2.2 x 108		Energy consumed by 60 W filament lightbulb in 1000 hours lifetime.
3.7 x 109		Potential energy of satellite-Earth system: 1000 kg satellite at 400 km altitude
2.9 x 1010		Kinetic energy of 1000 kg satellite in 400 km altitude low-Earth orbit This is roughly eight times the potential energy of raising the satellite to this altitude.
9.0 x 1016		Rest-mass energy of one kilogram of mass
1 x 1019		Annual electrical consumption of USA (1999)
1.77 x 1032		Difference in kinetic (or potential) energy for Earth (or Earth-Sun system) at perihelion and aphelion
2.65 x 1033		Kinetic energy of Earth, in the Sun's rest frame
-5.30 x 1033		Gravitational potential energy of the Sun and Earth, relative to infinite separation

Frequency

This section is for cyclical or periodic phenomena other than those involving rotations or revolutions, which are covered in the section "speed, angular or rotational"

Value, in hertz	Alternative Units	Description
50 or 60		Household electrical outlet
20 - 20,000		Audible sound
1 x 106		1000 kHz AM radio frequency
1 x 108		100 MHz FM radio frequency
2.45 x 109		Microwave oven frequency
9.19 x 109		Frequency of cesium-133 hyperfine transition used to define the second
4.3-7.5 x 1014		Frequency of visible light (700-400 nm wavelength)

Mass

Alternate units include milligrams (mg), grams (g), (avoirdupois or av.) ounces and pounds (lbs), and solar masses.

Value, in kilograms	Alternative Units	Description
9.1 x 10-31		Electron
1.7 x 10-27	1836 times the mass of the electron	Proton, or hydrogen atom
3.5 x 10-25		Lead-208, the heaviest stable atomic isotope
1.2 x 10-5	12 mg	Housefly
0.040	40 g	Standard-velocity 0.22 caliber bullet
0.24	240 grams, 8.3 ounces	8 fluid ounces of water
4-8	10-20 lbs	House cat
75	165 lbs	Human (typical)
1-2 x 105	200,000-400,000 lbs, 100-200 tons	Blue whale
6 x 109	6 billion kg, 13 billion lbs	Great Pyramid at Giza, Egypt
6 x 1010	60 billion kg, 130 billion lbs	Three Gorges Dam, Hubei province, China
5 x 1018	1 x 1019 lbs	Earth's atmosphere
1.4 x 1021	3 x 1021 lbs	Earth's oceans
7.3 x 1022		The Moon
6.0 x 1024		Earth
1.9 x 1027		Jupiter
2.0 x 1030	1 solar mass	The Sun
1.5 x 1031	7.5 solar masses	Betelgeuse, a supergiant star
1.3 x 1032	65 solar masses	Total mass of binary black hole system in first-ever detection of gravitational waves (2015)
8.2 x 1036	4.1 x 106 solar masses	Black hole at center of Milky Way galaxy
1 x 1040	6-7 x 109 solar masses	Black hole in M87, the first black hole ever imaged (2019)
1 x 1042	5 x 1011 solar masses	Milky Way galaxy (our galaxy)
2-3 x 1042		Local group of galaxies
2-3 x 1045		Local (Virgo) supercluster of galaxies

Temperature

While Celsius and Fahrenheit are two commonly used temperature scales, for comparison purposes it is best to use an absolute temperature scale, so Kelvins (K) are the main units in the listings below.

Value, in Kelvins	Alternative Units	Description
0	-273 C, -460 F	Absolute zero
2.7		Cosmic microwave background
4.2 and less		Liquid helium
20 and less		Liquid hydrogen
77 and less		Liquid nitrogen
90 and less		Liquid oxygen
184	-89 C, -128 F	Coldest recorded (natural) temperature on Earth (Vostok Station, Antarctica, on July 21, 1983)
195 and less	-78 C, -109 F	"Dry ice", frozen carbon dioxide
273	0 C, 32 F	Water freezes, or cold weather
293-296	20-23 C, 68-73 F	Room temperature, or mild weather
310	37.0 C, 98.6 F	Human body temperature, or very hot weather
373	100 C, 212 F	Water boils
450	177 C, 350 F	Moderately hot household oven
530	260 C, 500 F	Very hot household oven
770	500 C, 930 F	Faintly red-hot object
970	700 C, 1300 F	Moderately red-hot object
2800	2500 C, 4600 F	Tungsten lightbulb filament (typical), a white-hot object
5800	5500 C, 9900 F	The Sun's surface
10,000	9700 C, 17,500 F	Surface of a blue-hot star. Examples: Sirius is 9940 K. Rigel is 11,000 K.
1.5 x 107	1.5 x 107 C, 2.7 x 107 F	The Sun's center

Time

Note, the repeat periods of cyclical phenomena, like the cycle time of a typical sound frequency, are not generally included here. Doing so would simply repeat information that can be found in the frequency section of this article. An exception is made for the period of rotation or revolution of astronomical bodies such as Earth or the Moon, since these have historically served as standard definitions of time intervals like the day or the year.

Value, in seconds	Alternative Units	Description
5.39 x 10-44		Planck time
1.1 x 10-10		Period of cesium-133 hyperfine transition used to define the second
1.6 x 10-9		Lifetime of the first excited state of a hydrogen atom
0.2		Human reaction time (typical)
1.3		Light travel time, Earth to the Moon (one-way)
500	8.3 minutes	Light travel time, Earth to the Sun (one-way)
5500	92 minutes	Orbital period of satellite at 400 km altitude
8.64 x 104		1 Day
2.36 x 106	27.3 days	Orbital period of the Moon
2.55 x 106	29.5 days	Synodic period of the Moon, or period of the Moon's phases
3.16 x 107	1 Year	Orbital period of Earth
2.4 x 109	76 years	Human lifetime (typical)
7.8 x 109	248 years	Orbital period of Pluto
1.2 x 1013	380 x 103 years	Age of the universe when neutral hydrogen atoms formed
6.2 x 1015	0.20 billion years	Orbital period of the Sun around the galaxy
1.4 x 1017	4.5 billion years	Age of the solar system
4.3 x 1017	13.7 billion years	Age of the universe

Speed

Value, in meters per second	Alternative Units	Description
2 x 10-9	6 cm or 2 inches per year	Rate of separation of Africa and South America
1 x 10-7	3 inches per week	Rate at which grass grows (est.)
7 x 10-6		Tip of hour hand on a wall clock (2" length)
2 x 10-4		Tip of minute hand on a wall clock (4" length)
0.01		Tip of second hand on a wall clock (4" length)
0.03	1 inch per second	Insect walking
1.3	3 miles per hour (mph)	Human walking
6.7	"4-minute mile"	Fast human distance runner
10		Fast human sprinter
27	60 mph	Automobile highway speed
107	240 mph	Approx. top speed of Indy race car
343		Speed of sound (dry air, atmospheric pressure, 20 C temperature) Standard muzzle velocity of 0.22 caliber long rifle
460		Speed of Earth's surface at equator
510		Speed (rms) of air molecule at around room temperature (27 C, 300 K)
1020		The Moon (relative to Earth)
2700		Speed (rms) of a hydrogen atom at around room temperature (27 C, 300 K)
3100		Satellite in geosynchronous orbit (rela. to Earth)
4700		Pluto (rela. to the Sun)
7670		Satellite in low-Earth orbit (400 km altitude)
3.0 x 104		Earth (rela. to the Sun)
4.8 x 104		Mercury (rela. to the Sun)
2 x 105	c/1500	The Sun (rela. to the center of our galaxy
2.2 x 106	c/137	Speed of electron in hydrogen ground state (Bohr model)
2 x 108	(2/3)c	Speed of light in glass Speed of electronic signal in typical coaxial cable
2.6 x 108	0.87c	Speed of an object when its kinetic energy is equal to its rest mass energy mc2
3 x 108	186,000 miles per second	The speed of light, c

Speed, angular or rotational

This section is for rotational (spinning) motion or the revolution (orbiting) of an object about another object. For non-rotational, periodic phenomena, see the frequency section.

Value, in cycles per second (hertz)	Alternative Units	Description
3.17 x 10-8	Once per year	Revolution of Earth about the Sun
1.16 x 10-5	Once every 23 hours, 56 minutes, and 4 seconds, or roughly once per day	Rotation of Earth about its axis
0.0167	1 rpm	One revolution per minute
12.5	750 rpm	Car engine, idling
83-100	5000-6000 rpm	Car engine, typical maximum speed