ISO 129-1-2018 PDF

Full title and description

Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 1: General principles. ISO 129-1:2018 establishes the general principles and graphical conventions for presenting dimensions and associated tolerance information on technical drawings (primarily 2D) and provides concepts that can be applied to 3D documentation. It defines dimensioning elements, layout rules, symbols and notes to ensure clear, unambiguous technical product documentation across disciplines.

Abstract

ISO 129-1:2018 defines the general rules for the presentation of dimensions and associated tolerances in technical product documentation. It covers dimension lines, extension lines, leader lines, values and units, tolerance expression, special dimension types (diameters, radii, angles, spheres, arcs), arrangement of dimensions, and introduces property indicators, flag notes and textual instructions. The standard does not define tolerancing principles themselves (see ISO 14405‑1 and other GPS standards) and is intended to describe nominal models rather than non‑ideal (skin) models used for tolerancing.

General information

• Status: Published; edition confirmed by ISO review (confirmed 2023).
• Publication date: February 2018 (Edition 2). Amendment 1 published March 2020.
• Publisher: ISO — International Organization for Standardization.
• ICS / categories: 01.100.01 — Technical drawings in general / Technical product documentation.
• Edition / version: Edition 2 (2018) with Amendment ISO 129-1:2018/Amd 1:2020.
• Number of pages: 68 (ISO edition; national translations/endorsements may show different page counts due to forewords or added material).

Scope

Gives the general principles for indicating dimensions and associated tolerances on technical product documentation for all engineering fields, primarily focused on 2D drawings but applicable to 3D documentation practices. It specifies graphical conventions and rules for dimensioning and tolerance indication, symbols, and notes, while excluding the interpretation and application of tolerance principles themselves (covered by GPS/tolerancing standards such as ISO 14405‑1). The standard also notes additional guidance for construction engineering in related documents.

Key topics and requirements

• Principles for clear and unambiguous presentation of dimensions and tolerances on drawings.
• Definition and graphical representation of dimension elements: dimension lines, extension lines, leader lines, and arrows.
• Rules for dimension values, units, decimal notation and the presentation of nominal values.
• Methods for indicating limits, deviations and limit dimensions (limit dimensions, fit indications are referenced but tolerancing interpretation is covered elsewhere).
• Special dimension types: diameters, radii, spheres, arcs, chords, angles, squares and repetitive/equidistant features.
• Arrangement of dimensions: parallel, series, coordinates, stacked/tabular and combined dimensioning conventions.
• Use of property indicators, surface/developed length indicators, flag notes and textual instructions for additional specification.
• Guidance on ambiguity avoidance (when tolerance indication is unambiguous and when it is not) and references to GPS/tolerancing standards for interpretation.

Typical use and users

Used by mechanical and civil engineers, draughtsmen/drafters, CAD technicians, product designers, quality/inspection engineers, technical authors, and standards professionals to create consistent, machine- and human-readable drawings and documentation. It is applied in manufacturing, assembly, procurement documentation, technical training and in organizations harmonizing drawing practices across teams or suppliers.

Related standards

Part of the broader ISO/TPD and GPS ecosystem. Key related standards include other parts of the ISO 129 series (e.g., parts addressing mechanical engineering, shipbuilding and steel structures), ISO 14405 (tolerancing principles and interpretation), ISO 128 series (general drawing presentation rules), ISO 25178‑1 (surface texture indication) and ISO 1101 and other GPS standards for geometric tolerancing and specification. Regional/adopted versions (EN/ISO, national adoptions) may exist.

Keywords

dimensioning, tolerancing, technical drawings, TPD, dimension lines, extension lines, leader lines, units, limit dimensions, property indicators, flag notes, ISO 129, presentation of dimensions

FAQ

Q: What is this standard?

A: ISO 129-1:2018 is the International Standard that sets general principles and graphical conventions for presenting dimensions and associated tolerances in technical product documentation (mainly 2D drawings).

Q: What does it cover?

A: It covers rules for dimension elements and layout, notation of values and units, special dimension types (diameters, radii, angles, spheres, etc.), arrangement of dimensions, symbols and notes, and introduces property indicators and flag notes. It does not define tolerancing interpretation rules (those are covered by GPS/tolerancing standards such as ISO 14405‑1).

Q: Who typically uses it?

A: Engineers, CAD drafters, technical illustrators, quality and inspection personnel, manufacturing planners, and standards/technical documentation teams who must produce consistent and unambiguous engineering drawings and related documentation.

Q: Is it current or superseded?

A: This edition (Edition 2, published February 2018) is the current ISO edition and was confirmed in ISO’s periodic review. It superseded the 2004 edition. An amendment (ISO 129-1:2018/Amd 1) was published in March 2020 to update specific content.

Q: Is it part of a series?

A: Yes. ISO 129-1 is Part 1 (general principles) of the ISO 129 series covering indication of dimensions and tolerances; other parts address domain-specific dimensioning (mechanical engineering, shipbuilding, steel structures, simplified dimensioning, etc.) and the series is linked to related drawing and GPS standards.

Q: What are the key keywords?

A: Dimensioning, tolerancing, technical product documentation (TPD), dimension lines, extension lines, leader lines, limit dimensions, property indicators, flag notes, ISO 129.