Conversion of Units

This is a new unit conversion tool that was written in C++ in order to support the communication of medical information. The class Unit (hierarchy) works based on a concept of a minimal vector of basic dimensions. However, I decided to change the set of SI base units but you will not notice it and the conversions are of course SI compliant.

What is special about this unit converter is that you can prepend any ISO prefix to any unit (like k for km of f for fm). Since the prefices are handled separately from the units, the database of known units is quite compact and very easy to extend. The most important feature is that you cannot just enter simple (``atomic'') units but also any valid ISO-2955 term like: kg.m/s2.

Even those units which are usually tricky to convert are supported like:

• m (Hg) or m (H2O)
• Units with non-proportional conversions, like °F and °C or various units of level, like bel, dB (SPL, V, mV, µV, W, mW ...).
• pH which is convertible to mol/l and vice versa (of course).

Unlike SI, I do not regard the mole as a special dimension, but rather handle it as Avogadro's number. Thus you can convert mol/l into /l. (Did you know that a solution of pH 4 has about 60 free protons per atto-liter? Try it: convert 4 ph to /al!)

The class Unit is currently integrated in a much larger class library for medical communication and does depend on it. I did not had the time to reduce the dependencies in order to make this units converter an independent program. Contact me, if you are interested in it, so we can find a way.

Available Units

The following table shows any unit that is currently known to the converter. It is prepared for HTML but reflects quite well how easily you can add new units to the database.

Symbol	Type as	Name	Definition	Dimension
Base Units
m	m	meter		[1,0,0,0,0,0,0],0
s	s	second		[0,1,0,0,0,0,0],0
g	g	gram		[0,0,1,0,0,0,0],0
C	c	Coulomb		[0,0,0,1,0,0,0],0
K	k	Kelvin		[0,0,0,0,1,0,0],0
cd	cd	candela		[0,0,0,0,0,1,0],0
circ	circ	circle		[0,0,0,0,0,0,1],0
Pseudo Units, i.e. those whose dimension is 1
1	1	one		[0,0,0,0,0,0,0],0
10	10*	ten		[0,0,0,0,0,0,0],1
%	%	percent	1 10*-2
Angle
rad	rad	radian	1.5915494309189533577 10*-1.circ
sr	sr	steradian	4.0528473456935108578 10*-1.circ+2
°	deg	degree (angular)	2.7777777777777777778 10*-3.circ
"	mnt	angular minute	1.6666666666666666667 10*-2.deg
Space
l	l	liter	1 dm3
Time
h	hr	hour	3.6 10*3.s
min	min	minute	6 10*1.s
d	d	day	8.64 10*4.s
ann	ann	year	3.1536 10*7.s
Hz	hz	Herz	1 /s
Mechanics
N	n	Newton	1 kg.m/s2
p	p	pond	9.80665 g.m/s2
J	j	Joule	1 n.m
cal	cal	calorie	4.1868 j
W	w	Watt	1 j/s
Pa	pal	Pascal	1 n/m2
bar	bar	bar	1 10*5.pal
m (H2O)	m(h2o)	meter of water column	9.806650 kpal
m (Hg)	m(hg)	meter of mercury column	133.3220 kpal
Temperature
°C	cel	degree Celsius	cel_f(1 k)
°F	degf	degree Fahrenheit	degf_f(0.5555555555555555556 k)
Electromagnetism
A	a	Ampere	1 c/s
V	v	Volt	1 j/c
Ohm	ohm	Ohm	1 v/a
S	sie	Siemens	1 a/v
F	f	Farad	1 c/v
Wb	wb	Weber (magnetic flux)	1 v.s
T	t	Tesla (magnetic inductance)	1 wb/m2
H	hy	Henry (inductance)	1 wb/a
Photometric Units
lm	lm	lumen (luminous flux)	1 cd/sr
lx	lx	lux (illuminance)	1 lm/m2
Nuclear/Atomic/Molecular/Chemical
mol	mol	mole, Avogadro's number	6.022137 10*23
val	val	val, equivalents	6.022137 10*23
eq	eq	equivalents	6.022137 10*23
pH	ph	pH	ph_f(1 mol/l)
e	e	elementary charge	1.6021892 10*-19.c
eV	ev	electronvolt	1.602177 10*-19.j
u	u	atomic mass unit	1.6605655 10*-24.g
Bq	bq	Bequerel (activity)	1 /s
Gy	gy	Gray (energy dose)	1 j/s
Levels
bel	bel	bel	f_ln(1 1)
dB (SPL)	db(spl)	decibel sound pressure	f_20_lg(2 10*-5.pal)
dB (V)	db(v)	decibel volts	f_20_lg(1 v)
dB (mV)	db(mv)	decibel millivolts	f_20_lg(1 mv)
dB (uV)	db(uv)	decibel mycrovolts	f_20_lg(1 uv)
dB (W)	db(w)	decibel watts	f_10_lg(1 w)
dB (kW)	db(kw)	decibel kilowatts	f_10_lg(1 kw)
Biological/Biochemical/Medical Units
Sv	sv(a)	Sievert (alpha rays)	0.04 gy
Sv	sv(b)	Sievert (beta rays)	1 gy
Sv	sv(g)	Sievert (gamma rays)	1 gy
Sv	sv(x)	Sievert (X-rays)	1 gy
Sv	sv(n)	Sievert (neutrons)	0.2 gy
Sv	sv(p)	Sievert (protons)	0.1 gy
tot	tot	particles total count	1 1
cfu	cfu	colony forming units	1 1
ppm	ppm	parts per million	1 10*-6
ppb	ppb	parts per billion	1 10*-9
i.U.	iu	international units	1 1
kat	kat	katal	1 mol/s

If you think this table contains errors or needs to be extended, please let me know!

Prefices