# The Measuring Instruments Regulations 2016, Paragraph 3.2


The MPE on lambda calculation is 0.3 %. The conventional true value is calculated according to the formula set out in point 5.3.7.3 of Regulation No 83 of the Economic Commission for Europe of the United Nations (UN/ECE).
For this purpose, the values displayed by the instrument are used for calculation.

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Source: https://www.legislation.gov.uk/uksi/2016/1153/schedule/1J/paragraph/3.2 (the official version)
Page: https://openlegislation.uk/measuring-instruments-regulations-2016/schedule-1J/paragraph-3.2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.