This guide provides accurate metric equivalents and conversion factors for over 10,000 scientific units, as well as detailed descriptions of over 2000. It covers the full range of science, technology and medicine and deals with the US customary, British, conventional metric, historic systems and SI units. One section allows a search by application area, whilst another details mathematical and physical constants. Appendices contain lists of national and international standardization organizations and there is also an English-French lexicon of terms.