Non-SI Units Used in the United States |
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See the explanatory Notes at the end of the page. |
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| Unit Name | Abbrev. | Definition | Quantity | Origin | ||
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| gal | Gal | 10 | mm/s2 | * | acceleration | 4 |
| mile per hour per second | mphps | 0.447 04 | m/s2 | * | acceleration | 5 |
| standard gravity or free fall | g | 9.806 65 | m/s2 | * | acceleration | 3 |
| second of arc (arc second) | " | 4.848 137 | µrad | angle, plane | 3 | |
| second of right ascension | s RA | 72.722 05 | µrad | angle, plane | 3 | |
| minute of arc (arc minute) | ' | 290.8882 | µrad | angle, plane | 3 | |
| mil (angular) (1/6400 circle) | mil | 0.981 748 | mrad | angle, plane | 6 | |
| minute of right ascension | m RA | 4.363 323 | mrad | angle, plane | 3 | |
| degree (arc degree) | o | 17.453 29 | mrad | angle, plane | 3 | |
| point (compass) (1/32 circle) | pt | 196.3495 | mrad | angle, plane | 3 | |
| hour of right ascension | h RA | 261.7994 | mrad | angle, plane | 3 | |
| revolution (turn) | r | 6.283 185 | rad | angle, plane | 3 | |
| percent grade | % | equation | angle, plane | 3 | ||
| pitch (roofs) | equation | angle, plane | 5 | |||
| square degree | deg2 | 304.617 42 | µsr | angle, solid | 3 | |
| revolution per minute | rpm | 104.72 | mrad/s | angular speed | 3 | |
| revolution per second | rps | 6.2832 | rad/s | angular speed | 3 | |
| barn | b | 100 | fm2 | * | area | 4 |
| circular mil (π/[0.5 mil]2) | cm | 506.7075 | µm2 | area | 5 | |
| square mil | sq mil | 645.16 | µm2 | * | area | 5 |
| circular inch (π/[0.5 in]2) ? | cir in | 5.067 075 | cm2 | area | 5 | |
| square inch | sq in | 645.16 | mm2 | * | area | 1 |
| square foot | sq ft | 929.0304 | cm2 | * | area | 1 |
| square yard | sq yd | 0.836 127 4 | m2 | area | 1 | |
| square (roofing) (100 ft2) | sq | 9.29 | m2 | area | 5 | |
| acre (commercial) (36 000 ft2) | ac | 3344.523 | m2 | area | 6 | |
| acre (US survey) (43 560 ft2) | ac | 4046.873 | m2 | area | 1 | |
| square mile (International) | sq mi | 2.589 998 | km2 | area | 1 | |
| township | twp | 93.2 | km2 | area | 6 | |
| million acres | MMAc | 4047 | km2 | area | 6 | |
| Dobson unit | DU | 21.4 | mg/m2 | areal density | 6 | |
| "pound" (basis weight of book paper) | lb | 1.48 | g/m2 | areal density | 5 | |
| "pound" (basis weight of newsprint) | lb | 1.63 | g/m2 | areal density | 5 | |
| "pound" (basis weight of cover paper) | lb | 2.70 | g/m2 | areal density | 5 | |
| "pound" (basis weight of bond paper) (sub) | lb | 3.76 | g/m2 | areal density | 5 | |
| ounce per square yard ("ounce") | oz | 34 | g/m2 | areal density | 5 | |
| parts per million | ppm | 1 | mg/L | concentration | 6 | |
| parts per billion | ppb | 1 | µg/L | concentration | 6 | |
| parts per trillion | ppt | 1 | ng/L | concentration | 6 | |
| specific gravity (relative density) | sp gr | 1 | Mg/m3 | density | 3 | |
| degrees Baumé (heavy) ? | Bé | equation | density | 3 | ||
| degrees Baumé (light) ? | Bé | equation | density | 3 | ||
| degrees Twaddel ? | Two | equation | density | 3 | ||
| degrees Bark (tanning liquors) ? | oBk | equation | density | 3 | ||
| degrees Brix (sugar solutions) ? | oBrix | equation | density | 3 | ||
| degrees Beck ? | oBeck | equation | density | 3 | ||
| degrees API (API gravity) (petroleum) | G | equation | density | 6 | ||
| degrees Soxhlet (milk) ? | oSx | equation | density | 3 | ||
| degrees Ammoniameter (ammonia) ? | oAm | equation | density | 5 | ||
| degrees oleometer (vegetable oils) ? | equation | density | 5 | |||
| charge unit | e | 160.2189 | zC | electric charge | 3 | |
| faraday (carbon-12) ? | 96.4870 | kC | electric charge | 3 | ||
| mho | 1 | S | * | electric conductance | 3 | |
| ohm circular mil per foot | 1.662 426 | nW.m | electric resistivity | 5 | ||
| electronvolt | eV | 160.2189 | zJ | energy | 3 | |
| erg | erg | 100 | nJ | * | energy | 4 |
| ounce inch (ounce-force inch) ? | ozf.in | 7.061 553 | mJ | energy | 5 | |
| foot pound (pound-force foot) | ft.lb | 1.355 818 | J | energy | 5 | |
| calorie (thermochemical) | cal | 4.184 | J | * | energy | 4 |
| calorie (international table) | cal | 4.1868 | J | * | energy | 4 |
| liter atmosphere (45o latitude) | L.atm | 101.3 | J | energy | 4 | |
| British thermal unit (thermochemical) | Btu | 1.054 350 | kJ | energy | 5 | |
| British thermal unit (International table) | Btu | 1.055 056 | kJ | energy | 5 | |
| kip foot (1000 lbf.ft) | kip.ft | 1.356 | kJ | energy | 6 | |
| foot ton (ton-force foot) | ft.tonf | 2.711 636 | kJ | energy | 6 | |
| Calorie (nutritional) (ADA) | Cal | 4.186 | kJ | * | energy | 4 |
| horsepower hour | hp.h | 2.6856 | MJ | energy | 5 | |
| ton mile (ton-force mile) | tonf.mi | 14.32 | MJ | energy | 6 | |
| therm (GPA std) | th | 105.506 | MJ | energy | 5 | |
| refrigeration ton (US standard) ? | ton | 303.9 | MJ | energy | 6 | |
| million Btu (International table) | MMBtu | 1.056 | GJ | energy | 5 | |
| ton (nuclear devices) | t | 4.184 | GJ | * | energy | 6 |
| horsepower year | hp.yr | 23.526 | GJ | energy | 5 | |
| metric ton of coal equivalent (UN std) | mtce | 29.3076 | GJ | * | energy | 4 |
| metric ton of oil equivalent (1010 cal) | 41.84 | GJ | * | energy | 4 | |
| quad (Q-unit) | Qbtu | 1.055 | EJ | energy | 6 | |
| Richter magnitude | M |
equation |
energy | 6 | ||
| gallon (US) per day | gpd | 43.813 | µL/s | flow, volumetric | 6 | |
| cubic inch per minute ? | cim | 273.1 | µL/s | flow, volumetric | 5 | |
| gallon (US) per hour | gph | 1.0515 | mL/s | flow, volumetric | 6 | |
| cubic foot per hour | CFH | 7.866 | mL/s | flow, volumetric | 5 | |
| liter per minute | L/min | 16.666 | mL/s | flow, volumetric | 4 | |
| acre foot per year | af/y | 39.114 | mL/s | flow, volumetric | 6 | |
| gallon (US) per minute | gpm | 63.09 | mL/s | flow, volumetric | 6 | |
| cubic foot per minute | cfm | 471.95 | mL/s | flow, volumetric | 5 | |
| miners inch (ID, KS, NE, NM, NV, SD, UT) ? | 566.3 | mL/s | flow, volumetric | 5 | ||
| miner's inch (AZ, CA, MT, OR) | 707.9 | mL/s | flow, volumetric | 5 | ||
| miners inch (CO) ? | 737.4 | mL/s | flow, volumetric | 5 | ||
| gallon (US) per second | gps | 3.785 | L/s | flow, volumetric | 6 | |
| acre foot per day | af/d | 14.276 49 | L/s | flow, volumetric | 6 | |
| cubic foot per second (cusec, second foot) | cfs | 28.316 85 | L/s | flow, volumetric | 5 | |
| million gallons (US) per day | mgd | 43.812 64 | L/s | flow, volumetric | 6 | |
| dyne | dyn | 10 | µN | * | force | 4 |
| poundal ? | pdl | 138.255 | mN | force | 5 | |
| ounce-force ("ounce") | ozf | 278.0139 | mN | force | 5 | |
| pound-force (“pound”) | lbf | 4.448 222 | N | force | 5 | |
| kilogram-force (“kilogram”) | kgf | 9.806 65 | N | * | force | 4 |
| kip (kilopound-force) (1000 lbf) | kip | 4.448 222 | kN | force | 6 | |
| ton-force (2000 lbf) ("ton") | tonf | 8.896 | kN | force | 6 | |
| footcandle | fc | 10.764 | lx | illuminance | 4 | |
| phot ? | ph | 10 | klx | * | illuminance | 4 |
| exposure value | EV | equation | illuminance | 5 | ||
| magnitude (apparent stellar) | mag | equation | intensity | 3 | ||
| decibel (sound level) | dB | equation | intensity, sound | 4 | ||
| phon | equation | intensity, sound | 4 | |||
| sone | equation | intensity, sound | 6 | |||
| noy ? | equation | intensity, sound | 6 | |||
| langley (cal/cm2) | ly | 41.84 | kJ/m2 | * | irradiation | 6 |
| fermi ? | 1 | fm | * | length | 4 | |
| angstrom | Å | 100 | pm | * | length | 4 |
| microinch | µin | 25.4 | nm | * | length | 6 |
| micron | 1 | µm | * | length | 4 | |
| mil | mil | 25.4 | µm | * | length | 6 |
| caliber (US) | cal | 254 | µm | * | length | 6 |
| point (US printers) | pt | 351.4598 | µm | * | length | 6 |
| point (US computers) | pt | 352.8 | µm | length | 6 | |
| agate (1/14 inch) | 1.814 | mm | length | 6 | ||
| pica (US printers) | pca | 4.217 518 | mm | length | 6 | |
| pica (US computers) | pca | 4.233 | mm | length | 6 | |
| Powerpoint centimeter | cm | 1.0583 | cm | length | 6 | |
| inch | in | 2.54 | cm | * | length | 1 |
| hand | 10.16 | cm | * | length | 1 | |
| link (US survey) (1/100 chain) ? | li | 20.116 84 | cm | length | 1 | |
| foot (International) | ft | 30.48 | cm | * | length | 1 |
| foot (US survey) | ft | 30.480 061 | cm | length | 1 | |
| pace (military) (30 inches) | 76 | cm | length | 1 | ||
| yard | yd | 91.44 | cm | * | length | 1 |
| pace (geometrical) (60 inches) | 1.52 | m | length | 1 | ||
| fathom | fm | 1.8288 | m | length | 1 | |
| rod (US survey) (16.5 survey feet) ? | rd | 5.029 210 | m | length | 1 | |
| chain (US survey) | ch | 20.116 84 | m | length | 1 | |
| cable (US) (100 fathoms) ? | ca | 182.9 | m | length | 5 | |
| furlong | fur | 201.168 | m | length | 1 | |
| "klik" or "K" (slang) | 1 | km | * | length | 4 | |
| mile (International) | mi | 1.609 344 | km | * | length | 1 |
| mile (US survey) | mi | 1.609 347 | km | length | 1 | |
| mile (nautical) | NM | 1.852 | km | * | length | 3 |
| township or range | T or R | 9.66 | km | length | 6 | |
| light second | 300 | Mm | length | 3 | ||
| light minute | 18 | Gm | length | 3 | ||
| astronomical unit | AU | 149.5979 | Gm | length | 3 | |
| light year | ly | 9.46 | Pm | length | 3 | |
| parsec | pc | 30.857 | Pm | length | 3 | |
| American wire gauge | awg | varies | length | 6 | ||
| Birmingham wire gauge | BWG | varies | length | 6 | ||
| drill numbers | varies | length | 6 | |||
| nail penny | d | varies | length | 2 | ||
| screw numbers | # | varies | length | 6 | ||
| shotgun gauge | ga | varies | length | 5 | ||
| USS standard plate gauge | USS | varies | length | 6 | ||
| Washburn & Moen gauge | W&M | varies | length | 6 | ||
| vinyl gauge | ga | varies | length | 6 | ||
| men's shoe sizes (US) | equation | length | 6 | |||
| women's shoe sizes (US) | equation | length | 6 | |||
| children's shoe sizes (US) | equation | length | 6 | |||
| denier | 0.111 | mg/m | linear density | 4 | ||
| tex ? | 1 | mg/m | * | linear density | 4 | |
| nit ? | 1 | cd/m2 | * | luminance | 4 | |
| foot-lambert ? | ft-L | 3.426 | cd/m2 | luminance | 4 | |
| lambert ? | L | 1 | lm/cm2 | * | luminance | 4 |
| apparent foot-candle | fc | 10.76 | cd/m2 | luminance | 4 | |
| Einstein unit | EU |
equation |
luminous energy | 4 | ||
| lumerg ? | 1 | lm.s | * | luminous energy | 4 | |
| lumen hour | lm.h | 3600 | lm.s | * | luminous energy | 4 |
| mean spherical candlepower ? | MSCP | π/4 | lm | * | luminous flux | 4 |
| mean horizontal candlepower ? | MHCP | lm | luminous flux | 4 | ||
| candlepower (candle) | cp | 1 | cd | * | luminous intensity | 4 |
| oersted ? | Oe | 79.577 47 | A/m | magnetic field strength | 4 | |
| maxwell | Mx | 10 | nWb | * | magnetic flux | 4 |
| unit pole | 125.6637 | nWb | magnetic flux | 4 | ||
| gauss | Gs | 100 | µT | * | magnetic flux density | 4 |
| electron rest mass | me | 0.000 911 | yg | mass | 3 | |
| atomic mass unit (unified) (Dalton) | u | 1.660 566 | yg | mass | 3 | |
| "mig" (slang) | 1 | mg | * | mass | 4 | |
| point (jewelers) | pt | 2 | mg | * | mass | 3 |
| grain | gr | 64.798 91 | mg | * | mass | 1 |
| carat (metric) | ct | 200 | mg | * | mass | 3 |
| pennyweight (troy) | dwt | 1.555 174 | g | mass | 2 | |
| dram (avoirdupois) | dr | 1.771 845 | g | mass | 1 | |
| standard cubic foot (natural gas) | scf | 20.2 | g | mass | 5 | |
| ounce (avoirdupois) | oz | 28.349 523 | g | mass | 1 | |
| assay ton | AT | 29.167 | g | mass | 6 | |
| ounce (troy) | ozt | 31.103 477 | g | mass | 1 | |
| pound (avoirdupois) (poundmass) | lb | 453.592 37 | g | * | mass | 1 |
| bushel (oats) (USDA) | bu | 14.5 | kg | mass | 6 | |
| slug (gee-pound) | sl | 14.593 90 | kg | mass | 5 | |
| bushel (barley) (USDA) | bu | 21.8 | kg | mass | 6 | |
| bushel (shelled corn or rye) (USDA) | bu | 25.4 | kg | mass | 6 | |
| bushel (wheat, soybeans, potatoes)(USDA) | bu | 27.2 | kg | mass | 6 | |
| flask (mercury) | 34.5 | kg | mass | 5 | ||
| hundredweight (short or net) | cwt | 45.4 | kg | mass | 6 | |
| barrel (petroleum) | bbl | 135 | kg | mass | 6 | |
| ton (short or net) | tn | 907.185 | kg | mass | 6 | |
| metric ton | t | 1 | Mg | * | mass | 4 |
| ton (long, gross, or displacement) | T | 1016 | kg | mass | 1 | |
| body mass index | BMI | 1 | kg/m2 | * | mass per height squared | 4 |
| Btu per hour (international table) | BTUH | 293 | mW | power | 5 | |
| horsepower (mechanical) | hp | 745.7 | W | power | 5 | |
| refrigeration ton (US com'l) (200 Btu/min) | 3.517 | kW | power | 6 | ||
| solar luminosities | 383 | YW | power | 3 | ||
| energy efficiency ratio ([Btu/h]/W) | EER |
0.293 |
W/W | power ratio | 6 | |
| feet of air ? | 3.656 | Pa | pressure | 5 | ||
| millimeters of water | mmH2O | 9.8064 | Pa | pressure | 4 | |
| pound-force per square foot | psf | 47.88 | Pa | pressure | 5 | |
| millibar | mb | 100 | Pa | * | pressure | 4 |
| millimeter of mercury | mmHg | 133.322 | Pa | pressure | 4 | |
| inch of water (60 oF) | "WC | 248.84 | Pa | pressure | 5 | |
| ounce-force per square inch | ozi | 430.922 | Pa | pressure | 5 | |
| foot of water (39.2 oF) | ftWC | 2.988 98 | Pa | pressure | 5 | |
| inch of mercury (60 oF) | inHg | 3.376 85 | kPa | pressure | 5 | |
| pound-force per square inch | psi | 6.894 757 | kPa | pressure | 5 | |
| atmosphere (standard) | atm | 101.325 | kPa | * | pressure | 4 |
| kip per square inch | ksi | 6.894 757 | MPa | pressure | 6 | |
| decibel (sound pressure level) | dB |
equation |
pressure | 4 | ||
| rad | rd | 10 | mGy | * | radiation absorbed dose | 4 |
| rem | R | 10 | µSv | * | radiation dose equivalent | 4 |
| roentgen | R | 258 | µC/kg | radiation exposure | 4 | |
| curie | Ci | 37 | GBq | * | radioactivity | 4 |
| neper | Np |
equation |
ratio | 3 | ||
| foot per hour ? | fph | 84.66 | µm/s | speed | 5 | |
| inch per minute ? | ipm | 423.3 | µm/s | speed | 5 | |
| foot per minute | fpm | 5.08 | mm/s | * | speed | 5 |
| inch per second | ips | 25.4 | mm/s | * | speed | 5 |
| kilometer per hour | kph | 0.2777 | m/s | speed | 4 | |
| foot per second | fps | 0.3048 | m/s | * | speed | 5 |
| mile per hour | mph | 0.447 | m/s | speed | 5 | |
| knot | kt | 0.514 | m/s | speed | 3 | |
| mile per minute | mpm | 26.82 | m/s | speed | 5 | |
| Mach number | mach |
equation |
speed | 3 | ||
| mile per second | mps | 1.609 | km/s | speed | 5 | |
| speed of light | c | 299.792 458 | Mm/s | * | speed | 3 |
| degrees Fahrenheit | oF | equation | temperature | 5 | ||
| degrees Rankine | oR | equation | temperature | 5 | ||
| R-value | R | 0.1761 | K.m2/W | thermal insulance | 6 | |
| radar nautical mile ? | 12.261 | µs | time | 6 | ||
| second (sidereal) | s | 0.997 269 6 | s | time | 3 | |
| minute (sidereal) | m | 59.836 17 | s | time | 3 | |
| minute (solar) | min | 60 | s | * | time | 3 |
| hour (sidereal) | h | 3.590 170 | ks | time | 3 | |
| hour (solar) | h | 3.6 | ks | * | time | 3 |
| day (sidereal) | d | 86.164 09 | ks | time | 3 | |
| day (solar) | d | 86.4 | ks | * | time | 3 |
| week (work, 40 h) | wk | 144 | ks | time | 3 | |
| week (calendar) | wk | 604.8 | ks | time | 3 | |
| month (sidereal) | mo | 2.360 591 | Ms | time | 3 | |
| month (synodic or lunar) | mo | 2.551 443 | Ms | time | 3 | |
| month (mean calendar) | mo | 2.63 | Ms | time | 3 | |
| year (lunar) | 30.617 309 | Ms | time | 3 | ||
| year (common calendar, 365 d) | yr | 31.536 001 | Ms | time | 3 | |
| year (tropical or seasonal) | a | 31.556 926 | Ms | time | 3 | |
| year (sidereal) | 31.558 150 | Ms | time | 3 | ||
| year (anomalistic) | 31.558 430 | Ms | time | 3 | ||
| year (leap calendar, 366 d) | 31.622 401 | Ms | time | 3 | ||
| decade | 315.6 | Ms | time | 3 | ||
| century | 3.156 | Gs | time | 3 | ||
| millennium | 31.56 | Gs | time | 3 | ||
| dyne centimeter | dyn.cm | 0.1 | µN.m | * | torque | 4 |
| "ounce-inch" (ounce-force inch) | oz-in | 7.061 | mN.m | torque | 5 | |
| "inch-pound" (pound-force inch) | in-lb | 113 | mN.m | torque | 6 | |
| foot pound (pound-force foot) | ft.lb | 1.356 | N.m | torque | 5 | |
| centipoise | cp | 1 | mPa.s | * | viscosity, absolute | 4 |
| API "weight" (petroleum) |
equation |
viscosity, absolute | 6 | |||
| reyn (lbf.s/in2) ? | 6.894 76 | kPa.s | viscosity, absolute | 5 | ||
| gallon (US) per day per square foot | gpd/sf | 0.144 | mm2/s | viscosity, kinematic | 6 | |
| stokes (cm2/s) | st | 0.0001 | m2/s | viscosity, kinematic | 4 | |
| saybolt second ? | ? | viscosity, kinematic | 6 | |||
| redwood second ? | ? | viscosity, kinematic | 6 | |||
| drop | gtt | 50 | µL | * | volume | 6 |
| minim (US) ? | 61.61 | µL | volume | 1 | ||
| "mill" or "cc" (slang) | 1 | mL | * | volume | 4 | |
| teaspoon (US) | tsp | 5 | mL | volume | 1 | |
| tablespoon (US) | Tbsp | 15 | mL | volume | 1 | |
| cubic inch | cu in | 16.387 064 | mL | * | volume | 1 |
| fluid ounce (US) ("shot") | fl oz | 29.574 | mL | volume | 6 | |
| jigger (US) (1.5 fl oz) | ji | 44 | mL | volume | 6 | |
| cup (US) | C | 240 | mL | volume | 6 | |
| pint (US liquid) | pt | 473.2 | mL | volume | 1 | |
| pint (US dry) | pt | 550.6 | mL | volume | 1 | |
| bottle (wine) | 750 | mL | * | volume | 4 | |
| quart (US liquid) | qt | 946.4 | mL | volume | 1 | |
| liters per flush | Lpf | 1 | L | * | volume | 6 |
| quart (US dry) | qt | 1.101 | L | volume | 1 | |
| magnum | 1.5 | L | * | volume | 4 | |
| board foot | bf | 2.36 | L | volume | 1 | |
| gallon (US liquid) | gal | 3.785 | L | volume | ||