Countdown to a redefined International System of Units

Throughout history, measurement has been a fundamental part of human advancement. The oldest systems of weights and measures discovered date back over 4000 years. Early systems were tied to physical objects, like hands, feet, stones and seeds, and were used, as we still do now, for agriculture, construction, and trade. Yet, with new inventions and global trade more ever more accurate and unified systems were needed. In Europe, it wasn't until the 19th Century that a universally agreed measurement system began to be adopted and the International System of Units (SI units) was born.

Now, after years of hard work and scientific progress, we are ready once again to update and improve the SI units. The redefinition of the International System of Units enacted on the 16 November 2018 during the General Conference for Weights and Measures will mean that the SI units will no longer be based on any physical objects, but instead derived through fundamental properties of nature. Creating a system centred on stable and universal natural laws will ensure the long-term stability and reliability of measurements, and act as a springboard for the future of science and innovation.

The redefinition of the SI units will come into force on the 20th of May 2019, the anniversary of the signing of the Metre Convention in 1875, an international treaty for the international cooperation in metrology. To celebrate, we'll be counting down each of the SI units - the metre, second, kilogram, kelvin, mole, candela, and ampere.

Join us on the 20th of every month to find out where units are commonly used, how they're defined, and the changes that will take place!

The SI in the morning! Can you think of examples of where the kilogram, candela, kelvin, or mole are used in your life? You might even use all of them before lunchtime! Follow us and Europe's National Measurement Institutes and Designated Institutes using #SIredefinition #measurementscience

Next SI unit

Join us for the mole on 20 April 2019!