# Unit Conversions Made Simple

From the 6/10/08 issue of NIST Tech Beat, the e-newlsetter of the National Institute of Standards and Technology:

Relax, even scientists can sometimes use help when making conversions and measurements with the modern metric system, the International System of Units (known as SI from the French â€œLe Systeme International dâ€™Unitesâ€.) The good news is that the National Institute of Standards and Technology (NIST) has just released a guide for researchers, available to all, on correct SI usage and unit conversion.

NIST Special Publication (SP) 811, Guide for the Use of the International System of Units, complements the recently released U.S. version of the English language SI Brochure, SP 330, the eighth version of international standard reference guide to the modern metric system. (See â€œNIST Offers U.S. Interpretations of Recent SI (Metric) Changesâ€.)

SP 811 offers an extensive conversion factor appendix useful for measurement unit conversions and appropriate rounding strategies for data. It also provides an editorial checklist for reviewing manuscriptsâ€™ conformity with the SI and the basic principles of physical quantities and units. A color chart has been added that illustrates the utilization of the SI base units in defining the 22 derived units with special names and symbols.

NIST SP 811 and NIST SP 330 are available online . Printed copies can be requested with an email to TheSI@nist.gov.

1. David N8SRE says:

For people with less rigorous requirements, it’s worth noting that Google also does many unit conversions. You can do “searches” like:

10 inches in cm=
32 F in C=
10000 BTU/hr in watts=

and so on. Very handy as a quick reference. If you use Firefox the answer will pop up in a tooltip before you even hit Enter.

2. Eric WY7USA says:

Try this for antenna calculations

c / 14.150 Mhz * 0.95 / 2 in feet

3. David N8SRE says:

Slick!