Standards Development

Scope

This proposed standard prescribes rules for rounding off numerical values for the purpose of reporting results of a test, an analysis, a measurement or a calculation, and thus assisting in drafting specifications. It also makes recommendations as to the number of figures that should be retained in course of computation.

*Note The scope of ISO/TC 69 is standardization in the application of statistical methods, including generation, collection (planning and design), analysis, presentation and interpretation of data, and includes presentation and interpretation of data.

This NWIP in essence guides for presenting the result of measurement, test or of a calculation in rounded off form thus helps in interpretation of result, data.

Also ISO/TC 69/WG 3 deals with Statistical Interpretation of Data. This standard falls in category of ‘Measurement result and Interpretation of statistical Data’ as rounding off is applicable to the measurement result before reporting

Purpose

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To round off a value is to retain a certain number of figures, counted from the left, and drop the others so as to give a more rational form to the value.

The purpose of this proposal is to establish harmonized rules for rounding off numerical values and determining the number of figures to be retained when reporting results of tests, measurements, and calculations. Uniform rounding practices are essential to ensure consistency, comparability, and transparency of reported data across standards and applications. This standard supports reliable laboratory reporting, reproducible academic research, effective regulatory enforcement, and fair conformity assessment. It also brings customer confidence by ensuring clear, accurate, and trustworthy numerical information in specifications, test reports, and product declarations.

ISO 80000 1 Annex B only defines rounding range and integral multiples, without this broader terminology framework.

The proposed standard goes well beyond ISO 80000 1 Annex B in scope and operational detail. The main “extra” elements are:

i. Extra concepts and definitions:

The proposed standard defines “number of decimal places”, “number of significant figures” and “fineness of rounding” with worked examples, linking rounding explicitly to decimal places, significant figures and step size n.

ii. Additional rounding rules and shortcuts :

The proposed standard gives a full rule set (Rules I–VI) for:

Unit fineness rounding including the round to even rule for 5 Rounding to arbitrary fineness n via divide–round–multiply (Rule IV) Special shortcut rules for fineness based on 5 and 2 (Rules V and VI) useful in engineering (50, 0.5, 0.2, etc.).

iii. Treatment of safety limits and one direction rounding

The proposed standard formalizes one direction rounding where safety limits apply, and illustrates it with detailed conformity assessment examples (leakage current, cyanide in drinking water, minimum wall thickness, helmet impact).

iv. Guidance on computations and propagation of rounding:

The proposed standard devotes an entire clause to “Number of figures to be retained”, with rules for-addition and subtraction when operands have different accuracies multiplication and division, including when and how many extra figures to retain multi step computations, to control accumulation of rounding error worked numerical examples for each case.

v. Annex A justification and statistical rationale The proposed standard includes an annex that provides the rationale for the adopted rounding rules, particularly the use of round-to-even in halfway cases, demonstrating how this approach minimizes systematic bias in sums and averages over large datasets.

*Note:

Please refer to the note under section titled “Relation of the proposal to existing international standards and ongoing standardization work” for details of the limitations of ISO 80000-1 that this document seeks to address.