| c | The speed of light in vacuum |
| mu0 | The permeability of free space |
| e0 | The permittivity of free space |
| Na | Avogadro's number |
| F | The molar charge of 1 Faraday |
| k | The Boltzmann constant |
| R0 | The molar gas constant |
| V0 | The standard gas volume |
| Gauss | The magnetic field of 1 Gauss |
| mu | The length of 1 micron |
| ha | The area of 1 hectare |
| mph | The speed of 1 mile per hour |
| kmh | The speed of 1 kilometer per hour |
| au | The length of 1 astronomical unit (mean earth-sun distance) |
| G | The gravitational constant |
| ly | The distance of 1 light-year |
| pc | The distance of 1 parsec |
| g | The standard gravitational acceleration on Earth |
| ms | The mass of the Sun |
| e | The charge of the electron |
| eV | The energy of 1 electron volt |
| amu | The unified atomic mass |
| me | The mass of the electron |
| mmu | The mass of the muon |
| mp | The mass of the proton |
| mn | The mass of the neutron |
| alpha | The electromagnetic fine structure constant |
| Ry | The Rydberg constant |
| a0 | The Bohr radius |
| A | The length of 1 angstrom |
| barn | The area of 1 barn |
| muB | The Bohr Magneton |
| muN | The Nuclear Magneton |
| mue | The magnetic moment of the electron |
| mup | The magnetic moment of the proton |
| min | The number of seconds in 1 minute |
| h | The number of seconds in 1 hour |
| d | The number of seconds in 1 day |
| week | The number of seconds in 1 week |
| in | The length of 1 inch |
| ft | The length of 1 foot |
| yard | The length of 1 yard |
| mile | The length of 1 mile |
| mil | The length of 1 mil (1/1000th of an inch) |
| nmile | The length of 1 nautical mile |
| fathom | The length of 1 fathom |
| knot | The speed of 1 knot |
| pt | The length of 1 printer's point (1/72 inch) |
| texpt | The length of 1 TeX point (1/72.27 inch) |
| acre | The area of 1 acre |
| ltr | The volume of 1 liter |
| us_gallon | The volume of 1 US gallon |
| can_gallon | The volume of 1 Canadian gallon |
| uk_gallon | The volume of 1 UK gallon |
| quart | The volume of 1 quart |
| pint | The volume of 1 pint |
| pound | The mass of 1 pound |
| ounce | The mass of 1 ounce |
| ton | The mass of 1 ton |
| mton | The mass of 1 metric ton (1000 kg) |
| uk_ton | The mass of 1 UK ton |
| troy_ounce | The mass of 1 troy ounce |
| carat | The mass of 1 carat |
| gram_force | The force of 1 gram weight |
| pound_force | The force of 1 pound weight |
| kilepound_force | The force of 1 kilopound weight |
| poundal | The force of 1 poundal |
| cal | The energy of 1 calorie |
| btu | The energy of 1 British Thermal Unit |
| therm | The energy of 1 Therm |
| hp | The power of 1 horsepower |
| bar | The pressure of 1 bar |
| atm | The pressure of 1 standard atmosphere |
| torr | The pressure of 1 torr |
| mhg | The pressure of 1 meter of mercury |
| inhg | The pressure of 1 inch of mercury |
| inh2o | The pressure of 1 inch of water |
| psi | The pressure of 1 pound per square inch |
| poise | The dynamic viscosity of 1 poise |
| stokes | The kinematic viscosity of 1 stokes |
| stilb | The luminance of 1 stilb |
| lumen | The luminous flux of 1 lumen |
| lux | The illuminance of 1 lux |
| phot | The illuminance of 1 phot |
| ftcandle | The illuminance of 1 footcandle |
| lambert | The luminance of 1 lambert |
| ftlambert | The luminance of 1 footlambert |
| curie | The activity of 1 curie |
| roentgen | The exposure of 1 roentgen |
| rad | The absorbed dose of 1 rad |