International System of Units (SI) of 1960

What it is

In 1960 the CGPM named as the International System of Units a coherent set of six base units (metre, kilogram, second, ampere, kelvin and candela, with the mole added in 1971), with prefixes. That year the metre was redefined as 1,650,763.73 wavelengths of a krypton-86 line.

The SI derives from the MKSA system adopted earlier (1935-1948), from the CGS and from the metric system; the mole was added in 1971 and the 2019 redefinitions based it on fundamental constants. The krypton metre lasted until 1983.

What it led to

• a common language for science and industry
• redefinition of the metre by light (1983) and the 2019 SI revision
• ISO international standards for quantities and units

Built on

• Decimal metric system1795
• Metre Convention and the International Bureau of Weights and Measures1875
• Measurement of the metre in wavelengths (Michelson and Benoît)1892-1893

Made possible

• Metre defined by the speed of light1983
• Measurement of Planck's constant and redefinition of the kilogram2018-2019

Links

Sources✓ verified 2026-11-06

• https://en.wikipedia.org/wiki/International_System_of_Units
• https://es.wikipedia.org/wiki/Sistema_Internacional_de_Unidades