Image::ExifTool::MIEUnits − MIE units documentation


The MIE format allows units of measurement to be specified in brackets at the end of a MIE tag name (eg. "Volume(m3)"). This document describes the standard MIE units abbreviations.


The units string may contain any ASCII characters in the range 0x21 (’!’) to 0x7d (’}’), excepting the bracket characters (0x28 and 0x29). An empty string is allowed, and indicates a dimensionless value. Standard units should be used where possible. In the standard units, an underline (’_’) is used to indicate a subscript, and multiple words may be separated with a hyphen (’−’).

Exponents should be positive, and require no separator (eg. "m2" for square meters). Prefixes may be added to the standard units (eg. "cm") except when the resulting name conflicts with another standard unit.

Multiplication is indicated by ’.’, and division by ’/’. Reciprocal units (ie. the multiplicative inverse) are obtained through division rather than the use of negative exponents (eg. "/in", not "in−1"). In MIE units, multiplication has precedence over division, so everything to the right of a ’/’ is in the denominator. (See " EXAMPLES" for a few examples.)

Below is a table summarizing the special characters used in MIE units strings.

. multiplication
/ division (used for negative exponents)
− word separator
_ subscript
{} annotation
[] used to avoid name conflicts if necessary
0−9 exponentiation


[G] Newtonian constant of gravitation (unclassified)
[g] standard acceleration of free fall (acceleration)
[h] Planck constant (action)
[k] Boltzmann constant (unclassified)
{cfu} colony forming units (number)
{rbc} red blood cell count (number)
{tbl} tablets (number)
{tot} particles total count (number)
% percent (fraction)
10^N the number ten for arbitrary powers (number)
A Ampere (electric current)
a year (time)
a_g mean Gregorian year (time)
a_j mean Julian year (time)
a_t tropical year (time)
acr acre, U.S. (area)
acr_br acre, British (area)
Ao Angstrom (length)
APL−U APL unit (biologic activity of anticardiolipin IgA)
ar are (area)
arb−U arbitrary unit (arbitrary)
arcmin minute of arc (plane angle)
arcsec second of arc (plane angle)
atm standard atmosphere (pressure)
att technical atmosphere (pressure)
AU astronomic unit (length)
b barn (action area)
B bel (level)
B−kW bel kilowatt (power level)
B−mV bel millivolt (electric potential level)
B−SPL bel sound pressure (pressure level)
B−uV bel microvolt (electric potential level)
B−V bel volt (electric potential level)
B−W bel watt (power level)
bar bar (pressure)
bbl barrel (fluid volume)
Bd baud (signal transmission rate)
bdsk−U Bodansky unit (biologic activity of phosphatase)
beth−U Bethesda unit (biologic activity of factor VIII inhibitor)
bf board foot (volume)
Bi Biot (electric current)
bit bit (amount of information)
Bq Becquerel (radioactivity)
Btu British thermal unit (energy)
Btu_39 British thermal unit at 39 degF (energy)
Btu_59 British thermal unit at 59 degF (energy)
Btu_60 British thermal unit at 60 degF (energy)
Btu_IT international table British thermal unit (energy)
Btu_m mean British thermal unit (energy)
Btu_th thermochemical British thermal unit (energy)
bu bushel, U.S. (dry volume)
bu_br bushel, British (volume)
By byte (amount of information)
C Coulomb (electric charge)
c velocity of light (velocity)
cal calorie (energy)
Cal nutrition label Calories (energy)
cal_15 calorie at 15 degC (energy)
cal_20 calorie at 20 degC (energy)
cal_IT international table calorie (energy)
cal_m mean calorie (energy)
cal_th thermochemical calorie (energy)
car_Au carat of gold alloys (mass fraction)
car_m metric carat (mass)
cd candela (luminous intensity)
Cel degree Celsius (temperature)
Ch Charriere (gauge of catheters)
ch Gunter's chain, U.S. (length)
ch_br Gunter's chain, British (length)
Ci Curie (radioactivity)
cicero cicero (length)
circ circle (plane angle)
cml circular mil, international (area)
cr cord, international (volume)
crd_us cord, U.S. (fluid volume)
cup_us cup (volume)
d day (time)
deg degree (plane angle)
deg{mag} degree from magnetic north (plane angle)
degF degree Fahrenheit (temperature)
didot didot (length)
diop diopter (refraction of a lens)
dpt dry pint, U.S. (dry volume)
dqt dry quart, U.S. (dry volume)
dr dram (mass)
dr_ap dram, apothecary (mass)
drp drop (volume)
dye−U Dye unit (biologic activity of amylase)
dyn dyne (force)
e elementary charge (electric charge)
eps_0 permittivity of vacuum (electric permittivity)
eq equivalents (amount of substance)
erg erg (energy)
eV electronvolt (energy)
F Farad (electric capacitance)
fdr fluid dram, U.S. (fluid volume)
fdr_br fluid dram, British (volume)
foz fluid ounce, U.S. (fluid volume)
foz_br fluid ounce, British (volume)
ft foot, international (length)
ft_br foot, British (length)
ft_us foot, U.S. (length)
fth fathom, international (length)
fth_br fathom, British (length)
fth_us fathom, U.S. (length)
fur furlong, U.S. (length)
G Gauss (magnetic flux density)
g gram (mass)
g.m/{H−B} gram meter per heartbeat (prop. to ventricular stroke work)
g% gram percent (mass fraction)
Gal Gal (acceleration)
gal gallon, U.S. (fluid volume)
gal_br gallon, British (volume)
gal_wi historical winchester gallon (dry volume)
Gb Gilbert (magnetic tension)
gf gram−force (force)
gil gill, U.S. (fluid volume)
gil_br gill, British (volume)
gon gon (plane angle)
GPL−U GPL unit (biologic activity of anticardiolipin IgG)
gr grain (mass)
Gy Gray (energy dose)
H Henry (inductance)
h hour (time)
hd hand, international (height of horses)
hnsf−U Hounsfield unit (x−ray attenuation)
HP horsepower (power)
hp_C homeopathic potency of centesimal series (homeopathic potency)
hp_X homeopathic potency of decimal series (homeopathic potency)
HPF high power field (view area in microscope)
Hz Herz (frequency)
in inch, international (length)
in_br inch, British (length)
in_us inch, U.S. (length)
in−H2O inch of water column (pressure)
in−Hg inch of mercury column (pressure)
iU international unit (arbitrary)
J Joule (energy)
K Kelvin (temperature)
ka−U King−Armstrong unit (biologic activity of phosphatase)
kat katal (catalytic activity)
kg{wet−tis} kilogram of wet tissue (mass)
kn knot, international (velocity)
kn_br knot, British (velocity)
knk−U Kunkel unit (arbitrary biologic activity)
Ky Kayser (lineic number)
l liter (volume)
L liter (volume)
lb pound (mass)
lb_ap pound, apothecary (mass)
lb_tr pound, troy (mass)
lbf pound force (force)
lcwt long hunderdweight (mass)
ligne ligne (length)
lk link for Gunter's chain, U.S. (length)
lk_br link for Gunter's chain, British (length)
lm lumen (luminous flux)
Lmb Lambert (brightness)
lne line (length)
LPF low power field (view area in microscope)
lton long ton (mass)
lx lux (illuminance)
ly light−year (length)
m meter (length)
m_e electron mass (mass)
m_p proton mass (mass)
m−H2O meter of water column (pressure)
m−Hg meter of mercury column (pressure)
mclg−U Mac Lagan unit (arbitrary biologic activity)
mesh mesh, international (lineic number)
MET metabolic equivalent (metabolic cost of physical activity)
mg{creat} milligram of creatinine (mass)
mho mho (electric conductance)
mi mile, international (statute mile) (length)
mi_br mile, British (length)
mi_us mile, U.S. (length)
mil mil, international (length)
mil_us mil, U.S. (length)
min minute (time)
min_br minim, British (volume)
min_us minim, U.S. (fluid volume)
mo month (time)
mo_g mean Gregorian month (time)
mo_j mean Julian month (time)
mo_s synodal month (time)
mol mole (amount of substance)
MPL−U MPL unit (biologic activity of anticardiolipin IgM)
mu_0 permeability of vacuum (magnetic permeability)
Mx Maxwell (flux of magnetic induction)
N Newton (force)
nmi nautical mile, international (length)
nmi_br nautical mile, British (length)
Np neper (level)
Oe Oersted (magnetic field intensity)
Ohm Ohm (electric resistance)
osm osmole of dissolved particles (amount of substance)
oz ounce (mass)
oz_ap ounce, apothecary (mass)
oz_tr ounce, troy (mass)
P Poise (dynamic viscosity)
Pa Pascal (pressure)
pc parsec (length)
pc_br pace (length)
pca pica (length)
pca_pr Printer's pica (length)
pH pH (acidity)
ph phot (illuminance)
pi the number pi (number)
pied pied (length)
pk peck, U.S. (dry volume)
pk_br peck, British (volume)
pnt point (length)
pnt_pr Printer's point (length)
pouce pouce (length)
ppb parts per billion (fraction)
ppm parts per million (fraction)
ppth parts per thousand (fraction)
pptr parts per trillion (fraction)
PRU peripheral vascular resistance unit (fluid resistance)
psi pound per square inch (pressure)
pt pint, U.S. (fluid volume)
pt_br pint, British (volume)
pwt_tr pennyweight (mass)
qt quart, U.S. (fluid volume)
qt_br quart, British (volume)
R Roentgen (ion dose)
rad radian (plane angle)
RAD radiation absorbed dose (energy dose)
rch Ramden's chain, U.S. (length)
rd rod, U.S. (length)
rd_br rod, British (length)
REM radiation equivalent man (dose equivalent)
rlk_us link for Ramden's chain (length)
s second (time)
S Siemens (electric conductance)
sb stilb (lum. intensity density)
sc_ap scruple, apothecary (mass)
sct section (area)
scwt short hundredweight (mass)
smgy−U Somogyi unit (biologic activity of amylase)
sph spere (solid angle)
sr streadian (solid angle)
st stere (volume)
St Stokes (kinematic viscosity)
ston short ton (mass)
stone stone (mass)
Sv Sievert (dose equivalent)
Sv−U Svedberg unit (sedimentation coefficient)
T Tesla (magnetic flux density)
t tonne (mass)
tb−U tuberculin unit (biologic activity of tuberculin)
tbs tablespoon, U.S. (volume)
todd−U Todd unit (biologic activity antistreptolysin O)
tsp teaspoon, U.S. (volume)
twp township (area)
u unified atomic mass unit (mass)
U Unit (catalytic activity)
USP−U U.S. Pharmacopeia unit (arbitrary)
V Volt (electric potential)
W Watt (power)
Wb Weber (magnetic flux)
wk week (time)
yd yard, international (length)
yd_br yard, British (length)
yd_us yard, U.S. (length)


Standard SI prefixes:

y yocto (10^−24)
z zepto (10^−21)
a atto (10^−18)
f femto (10^−15)
p pico (10^−12)
n nano (10^−9)
u micro (10^−6)
m milli (10^−3)
c centi (10^−2)
d deci (10^−1)
da deka (10)
h hecto (10^2)
k kilo (10^3)
G giga (10^9)
M mega (10^6)
T tera (10^12)
P peta (10^15)
E exa (10^18)
Z zetta (10^21)
Y yotta (10^24)

Binary power prefixes:

Ki kibi (2^10)
Mi mebi (2^20)
Gi gibi (2^30)
Ti tebi (2^40)


A few examples of combined units strings:

/cm3 per cubic centimeter
in2 square inches
kg.m/s2 Newtons (N)
m3/kg.s2 units of [G]
10^100 googols


2006−12−14 − PH Created


Copyright 2003−2020, Phil Harvey (philharvey66 at

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.




Image::ExifTool::MIE(3pm), Image::ExifTool(3pm)