Overview
SIST EN ISO 7083:2021 (ISO 7083:2021) specifies recommended proportions and dimensions for symbols used in technical product documentation. The standard defines how symbols should be sized relative to drawing line width and lettering height, and provides tabulated dimensions and grid‑based proportions to ensure consistent, legible symbol production across technical drawings and documentation. It does not cover process‑plant symbols (see ISO 81714‑1).
Key topics and technical requirements
- Scope and basis
- Proportions are based on the standard lettering heights given in ISO 3098‑1.
- Symbols are sized according to a grid related to the chosen line width (stroke thickness).
- General conditions
- Lettering used with symbols shall conform to ISO 3098‑1.
- On a given drawing, symbol height, line width and lettering type should match the drawing’s dimensioning and indications.
- Symbols may be produced digitally, hand‑drawn (with rules), stencils, transfers or other appropriate methods.
- Dimension tables
- Recommended dimensions for two lettering types (examples from the standard):
- Lettering type A: frame heights H = 7, 10, 14, 20, 28, 40 mm; character heights h = 3.5 … 20 mm; line widths d = 0.25 … 1.4 mm.
- Lettering type B: frame heights H = 5, 7, 10, 14, 20, 28, 40 mm; character heights h = 2.5 … 20 mm; line widths d = 0.25 … 2.0 mm.
- Datum target indicator diameters and other characteristic sizes are given per table.
- Tolerance indicator frames and compartment widths are specified; distances between vertical strokes must be at least twice the line width, with a minimum of 0.7 mm.
- Proportions and grids
- Symbol configurations are depicted on a grid with spacing equal to the line width; tables provide sample proportions for many symbols.
- Symbol governance
- The document indexes symbols to the originating ISO standards and describes how new symbols are proposed, validated and registered.
Practical applications
- Create consistent, standardized engineering drawings, assembly instructions, parts catalogs and product manuals.
- Build compliant CAD symbol libraries, templates and title blocks for mechanical and technical drawing workflows.
- Ensure readable and interoperable technical product documentation across suppliers, manufacturers and regulatory submissions.
- Useful for QA checks to verify symbol sizing and legibility on printed and digital drawings.
Who should use this standard
- Mechanical drafters and CAD technicians
- Technical illustrators and documentation specialists
- Design engineers and product developers
- CAD standards administrators and quality managers
- Standards committees and technical publishers
Related standards
Using ISO 7083:2021 helps maintain consistent symbol proportions, improve drawing legibility, and streamline CAD library creation - essential for reliable technical product documentation.