ETBX Units Conversion Units

Units Conversion

An EngineersToolbox Calculation Module

Background Information

This module will convert a physical quantity, expressed in specified input units, to an equivalent value in specified output units.

Conversion factors stored in the ETBX units database are defined relative to a set of reference units in the International System of Units (SI). SI base units are consistent with the part of the metric system called the MKS (meter-kilogram-second) system. Table 1 lists the 17 quantity types supported by the ETBX Units Conversion module and the corresponding SI reference units.

Table 1. Unit types supported by the ETBX Units Conversion module

Category	Reference Units
Acceleration	meter per square second (m/s²)
Angle	radian (rad)
Area	square meter (m²)
Density	kilogram per cubic meter (kg/m³)
Distance	meter (m)
Energy	Joule (J)
Flow	cubic meter per second (m³/s)
Force	newton (N)
Frequency	hertz (Hz)
Mass	kilogram (kg)
Power	watt (W)
Pressure	pascal (Pa)
Temperature	kelvin (K)
Time	second (s)
Torque	newton meter (N-m)
Velocity	meter per second (m/s)
Volume	cubic meter (m³)

The 20 SI prefixes used to form decimal multiples and submultiples of SI units are given in Table 2. The Units Conversion module provides conversion factors for common prefixed unit types used in mechanical and civil engineering.

Table 2. SI Prefixes

Name	Symbol	Factor
yotta	Y	10²⁴
zetta	Z	10²¹
exa	E	10¹⁸
peta	P	10¹⁵
tera	T	10¹²
giga	G	10⁹
mega	M	10⁶
kilo	k	10³
hecto	h	10²
deka	da	10¹
deci	e	10^-1
centi	c	10^-2
milli	m	10^-3
micro	�	10^-6
nano	n	10^-9
pico	p	10^-12
femto	f	10^-15
atto	a	10^-18
zepto	z	10^-21
yocto	y	10^-24

Input

The Units Conversion module input form is shown in Figure 1. The Input list contains the unit type to be converted from. The Output list contains the unit type to be converted to. Enter the quantity of the input units in the Input Value field, and press the Calculate button. The converted quantity is displayed in the Output Value field.

Figure 1. Module input form

Output

The Units Conversion Module results report is shown in Figure 2.

Figure 2. Module results report

Links to Related Sites

NIST Metric Program - NIST is the National Institute of Standards and Technology, formerly known as the National Bureau of Standards, an agency of the U.S. Department of Commerce.
NIST Physics Laboratory Publications. At this web site you can read or download (in Adobe Acrobat format) official publications.
The International System of Units (SI). (1991) This is the official English-language description of the International System.
Guide to the Use of the International System of Units (SI). (1995) Rules and conventions for using SI units in the United States.
NIST Fundamental Physical Constants. Latest values of fundamental scientific constants (mass of the electron, Planck's constant, etc.), revised in 1998 to reflect recent experimental measurements.
Bureau International des Poids et M�sures. Home page for the international organization that maintains the SI.
A Dictionary of Units of Measurement. Comprehensive dictionary of units of measurement covering the English customary systems, the metric system, and the International System of Weights and Measures (SI).
A Dictionary of Units. Includes a long list of very carefully computed and precise factors for converting traditional units into SI units.

References

Lindeburg, M.R. (1999) Engineering Unit Conversions, 4th edition, Professional Publications.

Mechtly, E. A. (1969) "The International System of Units - Physical Constants and Conversion Factors," Office of Technology Utilization - National Aeronautics and Space Administration, Washington D.C.

Pennycuick, C.J. (1988) Conversion Factors : Si Units and Many Others : Over 2100 Conversion Factors for Biologists and Mechanical Engineers Arranged in 21 Quick-Reference Tables, University of Chicago Press.

Wildi, T. (1995) Metric Units and Conversion Charts : A Metrication Handbook for Engineers, Technologists, and Scientists, 2nd Edition, IEEE.

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