New measurement scale approved, ronnagrams and quettameters among the new units


It is the first time in more than three decades that new prefixes have been added to the International System of Units (SI), the globally agreed upon standard for the metric system.
Ronnagrams and Quettameters are some of the new metric prefixes: international scientists meeting in France on 18 November voted to express the largest and smallest measurements in the world, driven by an ever-growing amount of data. To the array of well-known prefixes such as kilo and milli are added ronna (27 zeros after one) and quetta (with 30 zeros after one) for larger numbers, ronto (10 to the 27th negative power) and quecto(10 to the negative 30th power for smaller ones.


The change was voted on by scientists and government representatives from around the world attending the 27th General Conference on Weights and Measures, which regulates the SI and meets approximately every four years at the Palace of Versailles, west of Paris. The UK’s National Physical Laboratory, which has been spearheading the push for the new area codes, confirmed approval of the resolution in a statement.

They are likely to be used to describe computer data in the future, as will terabytes and megabytes. But the new prefixes could also be used for other measurements. (According to the latest issue of the journal Nature, the Earth weighs about 1 ronnagram ).

New words to describe huge numbers

Compared to 1 terabyte, which equals 1,000 gigabytes, one ronnabyte equals one quadrillion (one thousand million million, or 1,000,000,000,000) terabytes. To put some context, the Library of Congress (also known by the acronyms of LOC  or  Loc , is the national library of the United States of America, which has 158 million documents) holds about 10 terabytes of printed materials, according to as reported by the cloud storage company Backblaze. So one ronnabyte would contain a hundred trillion Libraries of Congress.


The need to approve these new measures arises from the fact that the amount of total data stored and generated will soon exceed the terms used to describe them. But we have been trying to put order on this issue for some time now.


Richard Brown, a manager at the National Physical Laboratory in Teddington, England, started work on a proposal several years ago. “When there is a need that is not met, there is also a risk that unofficial units will take hold and confusion will arise ,” he declared in 2019.

Brown said the annual volume of data generated globally has already exceeded 1 zettabyte (the equivalent of one billion terabytes), and the annual data generated is expected to exceed 1 yottabyte (one trillion terabytes) in the next decade. The new prefixes “will future-proof the measurement system for expressing these large amounts of data…and will allow for clear and unambiguous communication of these measurements for many years to come,” Brown said. The new prefixes and insights are available on Nature.

  • How many yottabytes in a quettabyte? Extreme numbers get new names. (



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