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
Density is a measure of how compact a material substance is. It can be calculated by dividing the total mass of a material sample by the sample's volume. Density can be thought of as a combined effect between how close together the atoms in a material are, as well as how massive the individual atoms are. In solids and liquids, the atoms or molecules are closer together than in a gas, so are considerably more dense than gases such as air.
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.
The SI unit of density is kilograms per cubic meter (kg/m3). Alternative units are grams per cubic centimeter (g/cm3).
Quick scale: The sun, while on average only 40% denser than water, is 160 times denser than water in its core. Common metals such as steel, copper, and lead are around 10 times denser than water, which is 800 times denser than air. Helium is roughly 1/7 the density of air.
| 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
1 trillionth |
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 (3.14159...), and Avogadro's number (6.02 x 1023.
Loosely speaking, numbers can be classified as either very small compared to the number 1, comparable to 1, or very large compared 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 | |
| 4.5 x 106
4.5 million |
Median population of a state in the U.S.A.
2010 census: average of Louisiana and Kentucky, the 25th- and 26th-most populous states, respectively | |
| 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 |
| 9.9 x 1024 | 16 moles | The number of molecules in 10 fluid ounces of water |
Distance, length, height
Distance, length, and height are what may typically come to mind upon hearing the phrase "take a measurement".
The SI unit of length is the meter (m). Alternative units include:
- Angstroms
- Inches
- Feet
- Miles
- Astronomical units (AU)
- Light years
- Parsecs
Quick scale: The Sun's diameter is about 100 times that of Earth, which is about 8 million times bigger than the height of a typical person. A person's height is about 250 times the size of a housefly, which in turn is about 60 million times bigger than the diameter of an atom of hydrogen.
| Value, in meters | Alternative Units | Description |
|---|---|---|
| 1.6 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 |
| 5.3 x 10-11
53 trillionths |
0.53 Angstroms | Radius of hydrogen atom (Bohr model) |
| 3 x 10-8
30 billionths |
30 nm | rhinovirus (cold virus) diameter |
| 0.8-1.2 x 10-7
80 to 120 billionths |
80-120 nm | Influenza virus diameter |
| 0.2-3 x 10-7
20 to 300 billionths |
20-300 nm | Virus diameter (typical range) |
| 4-7 x 10-7
400 to 700 billionths, or around half of one millionth |
400-700 nm | Wavelength range of visible light |
| 0.1-600 x 10-6
0.1 to 600 millionths |
Bacterium | |
| 1-2 x 10-5
10 to 20 millionths |
0.01-0.02 mm, 0.0004-0.0008 inches | Amoeba (typical) |
| 1 x 10-4
100 millionths |
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
4 million |
4000 km, 2500 miles | North America, width at approx. 40 degrees North latitude;
Los Angeles-to-New York distance |
| 1.3 x 107
13 million |
13,000 km, 7900 miles | Earth's diameter |
| 3.0 x 108
300 million |
190,000 miles | One light-second, the distance that light travels in one second |
| 3.8 x 108
380 million |
240,000 miles | Earth-Moon distance |
| 1.4 x 109
1.4 billion |
870,000 miles | The Sun's diameter |
| 1.5 x 1011
150 billion |
1 Astronomical Unit (AU)
93 million miles 150 million km |
Earth-Sun average distance |
| 4.5 x 1012
4.5 trillion |
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 | 2.5 million 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
150 trillionths |
938.3 MeV | Proton rest-mass energy |
| 5 x 10-5
50 millionths |
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) |
| 0.99 x 104
99,000 |
Energy to melt "10 fluid ounces" (300 g) of ice
Note: 10 fluid ounces of water are produced after melting. | |
| 1.2 x 105
120,000 |
Energy to heat 10 fluid ounces (300 g) of liquid water from 0 C to 100 C (32 F to 212 F) | |
| 6.7 x 105
670,000 |
Energy to boil 10 fluid ounces (300 g) of water | |
| 3.6 x 106
3.6 million |
1 kW-h | One kilowatt-hour
A good example benchmark to answer the question: How small is one joule of energy? |
| 2.2 x 108
220 million |
Energy consumed by 60 W filament lightbulb in 1000 hours lifetime. | |
| 3.7 x 109
3.7 billion |
Potential energy of satellite-Earth system: 1000 kg satellite at 400 km altitude | |
| 2.9 x 1010
29 billion |
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) | |
| 1.8 x 1032 | Difference in kinetic energy of Earth at perihelion and aphelion (relative to the Sun)
Difference in potential energy of 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
1 million |
1000 kHz AM radio frequency | |
| 1 x 108
100 million |
100 MHz FM radio frequency | |
| 2.45 x 109
2.45 billion |
Microwave oven frequency | |
| 9.19 x 109
9.19 billion |
Frequency of cesium-133 hyperfine transition used to define the second | |
| 4.3-7.5 x 1014
430 to 750 trillion |
Frequency of visible light (700-400 nm wavelength) |
Magnetic field (a.k.a. magnetic flux density)
Most of us are familiar with magnets in our everyday lives. This section lists the strengths of various magnetic phenomena.
The SI unit of magnetic field strength is the tesla (T). Alternative units are in gauss (G).
Quick scale: The magnetic field strength used for an MRI is between 50 to 300 times stronger than a common household refrigerator magnet, which in turn is 300 times stronger than Earth's magnetic field.
| Value, in tesla | Alternative Units | Description |
|---|---|---|
| 2.5 to 6.5 x 10-4
25 to 65 millionths |
0.25 to 0.65 G | Earth's magnetic field at Earth's surface (0.25 G near the equator, 0.65 G near the poles) |
| 0.01 | 100 G | Common household refrigerator magnet |
| 0.5 to 3 | Field used for MRI | |
| 45 | Highest human-made magnetic field, continuous use | |
| 100 | Highest human-made magnetic field, repeatable pulses (0.015 second pulse duration) |
Mass
Mass is the quantity of matter that comprises an object. Strictly speaking, mass is different than weight, which is the strength of the force (or "pull") of gravity on an object. A person standing on the Moon has the same mass, but less weight, than they do when standing on Earth.
The SI unit of mass is the kilogram (kg). Alternate units include:
- milligrams (mg)
- grams (g)
- avoirdupois ounces (oz), not to be confused with fluid ounces
- pounds (lbs)
- solar masses
Quick scale: The Sun's mass is about 300,000 times that of Earth, which is of order 1023 -- i.e., 1 followed by twenty-three 0s -- times that of a typical person. A typical person is about 6 million times more massive than a housefly, which in turn is of order 1022 times more massive than an atom of hydrogen.
| 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 millionths |
12 mg | Housefly |
| 0.040 | 40 g | Standard-velocity 0.22 caliber bullet |
| 0.30 | 300 grams, 10.4 ounces | 10 fluid ounces of water |
| 4-8 | 10-20 lbs | House cat |
| 75 | 165 lbs | Human (typical) |
| 1-2 x 105
100,000 to 200,000 |
200,000-400,000 lbs, 100-200 tons | Blue whale |
| 6 x 109
6 billion |
13 billion lbs | Great Pyramid at Giza, Egypt |
| 6 x 1010
60 billion |
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
15 million |
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
110 trillionths |
Period of cesium-133 hyperfine transition used to define the second | |
| 1.6 x 10-9
1.6 billionths |
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 |
| 86,400 | 1 Day | One day |
| 2.36 x 106
2.36 million |
27.3 days | Orbital period of the Moon |
| 2.55 x 106
2.55 million |
29.5 days | Synodic period of the Moon, or period of the Moon's phases |
| 3.16 x 107
31.6 million |
1 Year | Orbital period of Earth |
| 2.4 x 109
2.4 billion |
76 years | Human lifetime (typical) |
| 7.8 x 109
7.8 billion |
248 years | Orbital period of Pluto |
| 1.2 x 1013
12 trillion |
380,000 years | Age of the universe when neutral hydrogen atoms formed |
| 6.2 x 1015 | 200 million or 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
2 billionths |
6 cm or 2 inches per year | Rate of separation of Africa and South America |
| 1 x 10-7
100 billionths |
3 inches per week | Rate at which grass grows (est.) |
| 7 x 10-6
7 millionths |
Tip of hour hand on a wall clock (2" length) | |
| 2 x 10-4 or 0.0002
200 millionths |
Tip of minute hand on a wall clock (4" length) | |
| 0.01 | 1 cm or 0.4 inches per second | 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"
15 mph |
Fast human distance runner |
| 10 | 100 meters in 10 seconds
22 mph |
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) | |
| 30,000 | Earth (rela. to the Sun) | |
| 48,000 | Mercury (rela. to the Sun) | |
| 200,000 | c/1500 | The Sun (rela. to the center of our galaxy |
| 2.2 x 106
2.2 million |
c/137 | Speed of electron in hydrogen ground state (Bohr model) |
| 2 x 108
200 million |
(2/3)c | Speed of light in glass
Speed of electronic signal in typical coaxial cable |
| 2.6 x 108
260 million |
0.87c | Speed of an object when its kinetic energy is equal to its rest mass energy mc2 |
| 3 x 108
300 million |
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
317 billionths |
Once per year | Revolution of Earth about the Sun |
| 1.16 x 10-5
11.6 millionths |
Once every 23 hours, 56 minutes, and 4 seconds,
or roughly once per day |
Rotation of Earth about its axis |
| 0.0167 or 1/60 | 1 rpm | One revolution per minute |
| 0.556, 0.75, 1.3 | 33-1/3, 45, 78 rpm | Phonograph records
The progression from 78 to 33-1/3 rpm records is a mid-20th-century example of increasing data storage density. |
| 12.5 | 750 rpm | Car engine, idling |
| 83-100 | 5000-6000 rpm | Car engine, typical maximum speed |