AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020
Units of Measure
Abbreviations
Quantitative values may be reported in conventional units or by using the International System of Units (“SI units” [Système International d’Unités]) (see 17.5.10, Laboratory Values, and 17.1, SI Units). JAMA Network journals report most analytes in conventional units.
Use the following abbreviations and symbols with a numerical quantity in accordance with guidelines in 17.0, Units of Measure. See especially 17.5, Conventional Units and SI Units in JAMA Network Journals; 17.5.10, Laboratory Values; and 8.4, Forward Slash [Virgule, Solidus]).
In rare instances, it may be appropriate to use teaspoon, cup, pound, mile, and so on in a scientific article when, for example, describing a survey in which such units may have been used in the original questionnaire. Conventional-unit equivalents may then be included parenthetically or in an explanatory footnote (as in a table or figure).
Note: Do not capitalize abbreviated units of measure (unless the abbreviation itself is always capitalized or contains capital letters).
Abbreviations listed in this section can be used without expansion except where noted otherwise. The abbreviations for measures of time (day, hour, millisecond, minute, month, second, week, and year) should be used only in a virgule construction and in tables and figures.
Unit of measure |
Abbreviation |
acre |
acre |
ampere |
A |
angstrom |
Convert to nanometers (1 A = 0.1 nm) |
atmosphere, standard |
atm |
bar |
bar |
barn |
b (expand at first mention) |
base pair |
bp (expand at first mention) |
becquerel |
Bq |
billion electron volts |
GeV (expand at first mention) |
Bodansky unit |
BU (expand at first mention) |
British thermal unit |
BTU |
calorie |
cal |
candela |
cd (expand at first mention) |
Celsius |
C (See policy about use of degree symbols in 18.1.5, Measures of Temperature.) |
centigram |
cg |
centimeter |
cm |
centimeters of water |
cm H_{2}O |
centimorgan |
cM |
centipoise |
cP |
coulomb |
C (expand at first mention) |
counts per minute |
cpm |
counts per second |
cps |
cubic centimeter |
cm^{3} (use milliliter for liquid and gas measure; avoid cc) |
cubic foot |
cu ft |
cubic inch |
cu in |
cubic meter |
m^{3} |
cubic micrometer |
µm^{3} |
cubic millimeter |
mm^{3} (use microliter for liquid and gas measure) |
cubic yard |
cu yd |
curie |
Ci |
cycles per second |
Use hertz |
dalton |
Da |
day |
d (use only in virgule construction, tables, and figures) |
decibel |
dB |
decigram |
Convert to grams |
deciliter |
dL |
decimeter |
Convert to meters |
diopter |
D (expand at first mention) |
disintegrations per minute |
dpm (expand at first mention) |
disintegrations per second |
dps (expand at first mention) |
dyne |
dyne |
electron volt |
eV |
electrostatic unit |
ESU (expand at first mention) |
equivalent |
Eq |
Fahrenheit |
F (See policy about use of degree symbols in 18.1.5, Measures of Temperature.) |
farad (electric capacitance) |
F (expand at first mention) |
femtogram |
fg |
femtoliter |
fL |
femtomole |
fmol |
fluid ounce |
fl oz |
foot |
ft (convert to meters; query author) |
gas volume |
gas volume |
gauss |
G |
gigabyte |
GB |
grain |
grain |
gram |
g |
gravity (acceleration due to) |
g (use closed up to preceding number, eg, 200g) |
gray |
Gy |
henry |
H (expand at first mention) |
hertz |
Hz |
horsepower |
hp |
hour |
h (use only in virgule construction, tables, and figures) |
immunizing unit |
ImmU (expand at first mention) |
inch |
in |
international benzoate unit |
IBU (expand at first mention) |
international |
unit IU |
joule |
J |
katal |
kat (expand at first mention) |
kelvin |
K |
kilobase |
kb (expand at first mention) |
kilobyte |
kB |
kilocalorie |
kcal |
kilocurie |
kCi |
kilodalton |
kDa |
kiloelectron volt |
keV |
kilogram |
kg |
kilohertz |
kHz |
kilojoule |
kJ |
kilometer |
km |
kilovolt |
kV |
kilovolt-ampere |
kVA |
kilovolt (constant potential) |
kV(cp) (expand at first mention) |
kilovolt (peak) |
kV(p) (expand at first mention) |
kilowatt |
kW |
King-Armstrong unit |
King-Armstrong unit |
knot |
knot |
liter |
L |
lumen |
lumen |
lux |
lux |
megabyte |
MB |
megacurie |
MCi |
megacycle |
Mc |
megahertz |
MHz |
megaunit |
megaunit |
megawatt |
MW |
meter |
m |
metric ton |
metric ton |
microampere |
µA |
microcurie |
µCi |
microfarad |
µF (expand at first mention) |
microgram |
µg |
microliter |
µL |
micrometer |
µm |
micromicrocurie |
Use picocurie |
micromicrogram |
Use picogram |
micromicrometer |
Use picometer |
micromolar |
µM |
micromole |
µmol |
micron |
Use micrometer |
micronormal |
µN |
microosmole |
µOsm |
microvolt |
µV |
microwatt |
µW |
mile |
mile |
miles per hour |
mph |
milliampere |
mA |
millicurie |
mCi |
millicuries destroyed |
mCid (expand at first mention) |
milliequivalent |
mEq |
millifarad |
mF (expand at first mention) |
milligram |
mg |
milligram-element |
mg-el (expand at first mention) |
milli—international unit |
mIU |
milliliter |
mL |
millimeter |
mm |
millimeters of mercury |
mm Hg |
millimeters of water |
mm H_{2}O |
millimolar |
mM |
millimole |
mmol |
million electron volts |
MeV |
milliosmole |
mOsm |
millirem |
mrem |
milliroentgen |
mR |
millisecond |
ms (use only in virgule construction, tables, and figures) |
milliunit |
mU |
millivolt |
mV |
milliwatt |
mW |
minute (time) |
min (use only in virgule construction, tables, and figures) |
molar |
M |
mole |
mol |
month |
mo (use only in virgule construction, tables, and figures) |
morgan |
M (expand at first mention) |
megaunit |
MU (expand at first mention) |
mouse unit |
MU (expand at first mention) |
nanocurie |
nCi |
nanogram |
ng |
nanometer |
nm |
nanomolar |
nM |
nanomole |
nmol |
newton |
N |
normal (solution) |
N |
ohm |
Ώ |
osmole |
osm |
ounce |
oz |
outflow (weight) |
C (expand at first mention) |
parts per million |
ppm |
pascal |
Pa |
picocurie |
pCi |
picogram |
pg |
picometer |
pm |
picomolar |
pM |
picomole |
pmol |
pint |
pt |
pound |
lb (convert to milligrams, kilograms, or grams; query author) |
pounds per square inch |
psi |
prism diopter |
PD, Δ (expand at first mention) |
quart |
qt |
rad |
rad |
radian |
radian |
rat unit |
RU (expand at first mention) |
revolutions per minute |
rpm |
roentgen |
R |
roentgen equivalents human (or mammal) |
rem |
roentgen equivalents physical |
rep |
Saybolt seconds universal |
SSU (expand at first mention) |
second |
s (use only in virgule construction, tables, and figures) |
siemens |
S |
sievert |
Sv |
sp g |
specific gravity (use with a number, eg, sp g 13.6) |
square centimeter |
cm^{2} |
square foot |
sq ft |
square inch |
sq in |
square meter |
m^{2} |
square millimeter |
mm^{2} |
Svedberg flotation unit |
Sf (expand at first mention) |
terabyte |
TB |
tesla |
T |
torr |
Use millimeters of mercury |
tuberculin unit |
TU |
turbidity-reducing unit |
TRU (expand at first mention) |
unit |
U |
volt |
V |
volume |
vol |
volume per volume |
vol/vol |
volume percent |
vol% |
watt |
W |
week |
wk (use only in virgule construction, tables, and figures) |
weight |
wt |
weight per volume |
wt/vol |
weight per weight |
wt/wt |
yard |
yd |
year |
y (use only in virgule construction, tables, and figures) |