Generally

The formula is very helpful with recurring arithmetic operations. Instead of again and again new find out, what is to be done with the length and width of a rectangle, in order to calculate its area, one should generally note this approach. This can happen in the form

If one now uses the initial letters of the internationally valid, usually terms taken from the English language for the terms area, length and width, would have to stand there

A formula is thus a description, which arithmetic operations are to be applied to the designator necessary for the calculation.

Dimension/ identifier Si-Basic units boldface		Units	Conversation
	Angel (at the wheel)	° (grad)	1° = 60'  (angle minutes) 1 ' = 60" (angle seconds)
	Angel (at the steering wheel)	° (grad)
	(Ignition interval) angel	° (grad)
	Compression ratio
	Efficency
	Air/fuel ratio
	Friction
	circumference/diameter	3,14159 ...
	Density	g/cm³	1 g/cm³ = 1 kg/dm³ = 1 t/m³
	(Mechanical) tension	N/mm²
a	acceleration	m/s²
A	Area	mm², cm², dm², m², km²	1 km²=1.000.000 m² =10.000 cm² =100 dm²
b	Width	mm, cm, dm, m	1 m = 10 dm = 100 cm = 1000 mm
c	Fuel consumption	l/100 km
d	Diameter, bore	mm, cm	1 cm = 10 mm
E	Energy	Nm, Ws, J, kJ (Joule), kWh	1 Nm = 1 Ws = 1 J 1 kJ = 1000 J 1 kWh = 3600 kJ
f	Frequency	Hz (Herz), s-1 (1/s)	1 Hz = 1 Oszillation/s.
F	Force	N, daN, kN	1 kN = 100 daN 1 daN = 10 N 1 N = 1 kg·m/s²
g	Acceleration of gravity	9,81 m/s²
G	Weight	N, daN, kN	1 kN = 100 daN 1 daN = 10 N 1 N = 1 kg·m/s²
h	Height	mm, cm, dm, m	1 m = 10 dm = 100 cm = 1000 mm
i	Ratio
I	Current	A (Ampere)	1 A = 1000 mA
K	Capacitance	Ah (Amperehours)
l	Length	mm, cm, dm, m, km	1 Seemeile = 1,852 km 1 Landmeile = 1,609 km 1 km = 1000 m 1 m = 10 dm = 100 cm = 1000 mm 1 Inch = 25,4 mm
m	Mass	g, kg, t (Tonne)	1 t = 1000 kg 1 kg = 1000 g 1 pound (lb) = 453,59 g
M	Torque	Nm (Newtonmeter)	1 N · 1 m = 1 Nm
n	numbers of revolutions	s-1 (1/s) min-1 (1/min)	1 s-1 = 60 min-1
p	pressure	Pa (Pascal) mbar, bar, N/cm²	1 bar = 10 N/cm² 1 bar = 1000 mbar 1 bar = 100.000 Pa
P	Power	VA (Volt·Ampere), W (Watt), kW, PS (Horsepower)	1 W = 1 J/s = 1 Nm/s = 1 kg·m²/s³ 1 W = 1 VA 1 kW = 1000 W 1 kW = 1,3596 PS 1 PS = 735,5 W
Q	Heat quantity	Nm, Ws, J, kJ (Joule)	1 Nm = 1 Ws = 1 J 1 kJ = 1000 J
r	Radius, lever arm	mm, cm, dm, m	1 m = 10 dm = 100 cm = 1000 mm
R	Resistance	M, k, , m (Ohm)	1 M = 1000 k 1 k = 1000 1 = 1000 m
s	Distance, stroke	mm, cm, dm, m, km	1 km = 1000 m 1 m = 10 dm 1 dm = 10 cm 1 cm = 10 mm
t	Time (time)	h, min, s	1 h = 60 min 1 min = 60 s
t	Temperature	°C (grad Celsius)	0 °C = 32 °F, 100 °C = 212 °F
T	Periodic time	s (second)
T	Temperature	K (Kelvin)	0 °C = 273 K, 100 °C = 373 K
v	Velocity (velocity)	km/h	1 m/s = 3,6 km/h 1 km/h = 0,278 m/s
U	Voltage	V (Volt)	1 V = 1000 mV
V	Volume	mm³, cm³ (ml), dm³ (Liter), m³	1 m³ = 1000 dm³ (Liter) 1 dm³ (Liter) = 1000 cm³ (ml) 1 cm³ (ml) = 1000 mm³ 1 barrel = 159 dm³ (Liter) 1 gallon = 3,79 dm³ (Liter)
W	Work	Nm, Ws, J, kJ (Joule)	1 Nm = 1 Ws = 1 J 1 kJ = 1000 J