MechPilotISO 128-2 line types and line widths for technical drawings
The line types of technical drawings, what each is used for in mechanical engineering, and the widths a line may have.
Line widths
0.13 mm 0.18 mm 0.25 mm 0.35 mm 0.5 mm 0.7 mm 1 mm 1.4 mm 2 mm
Narrow lines are 0.5 × the width of wide lines. ISO 128-2:2020, 5.1 Line width: 'The width, d, of all types of lines shall be one of the following ... 0,13 mm; 0,18 mm; 0,25 mm; 0,35 mm; 0,5 mm; 0,7 mm; 1 mm; 1,4 mm; 2 mm.' and 'The widths of extra wide, wide and narrow lines are in the ratio 4:2:1.'
Line types
| No. | Line type | Width | Pattern (multiples of d) | Typical use |
|---|---|---|---|---|
| 01.1 | Continuous narrow | Narrow | continuous | Dimension lines, extension lines, leader lines, hatching, outlines of revolved sections, short centre lines, projection lines |
| 01.1-freehand | Continuous narrow freehand | Narrow | continuous | Limits of partial or interrupted views and sections, when the limit is not an axis |
| 01.1-zigzag | Continuous narrow with zigzags | Narrow | continuous | Limits of partial or interrupted views and sections, drawn by machine |
| 01.2 | Continuous wide | Wide | continuous | Visible edges and outlines, crests of screw threads, limit of length of full thread |
| 02.1 | Dashed narrow | Narrow | 12, 3 | Hidden edges and hidden outlines |
| 02.2 | Dashed wide | Wide | 12, 3 | Indication of permissible areas of surface treatment |
| 04.1 | Long-dashed dotted narrow | Narrow | 24, 3, 1, 3 | Centre lines, lines of symmetry, pitch circles of gears and of holes |
| 04.2 | Long-dashed dotted wide | Wide | 24, 3, 1, 3 | Indication of cutting planes, indication of limited required areas of surface treatment |
| 05.1 | Long-dashed double-dotted narrow | Narrow | 24, 3, 1, 3, 1, 3 | Outlines of adjacent parts, extreme positions of movable parts, centroidal lines, initial outlines prior to forming, parts in front of a cutting plane |
ISO 128-2:2020, 5.3 Table 4 Lengths of line elements: dot <= d (types 04 to 07, 10 to 15); gap 3d (02, 04 to 15); short dash 6d (08, 09); dash 12d (02, 03, 10 to 15); long dash ~24d (04 to 06, 08, 09); space 18d (03). Patterns below are [element, gap, ...] in multiples of the line width d; dots use d.
Sources of each line type
- 01.1: ISO 128-2:2020, Table 1 no. 01 (continuous) with Table 2 sub-type .1 (narrow); applications in Annex D (mechanical engineering)
- 01.1-freehand: ISO 128-2:2020, Table 1 no. 01 with Table 3 variation 'Freehand / freeform curve continuous line'; applications in Annex D
- 01.1-zigzag: ISO 128-2:2020, Table 1 no. 01 with Table 3 variation 'Uniform zigzag continuous line'; applications in Annex D
- 01.2: ISO 128-2:2020, Table 1 no. 01 with Table 2 sub-type .2 (wide); applications in Annex D
- 02.1: ISO 128-2:2020, Table 1 no. 02 (dashed), Table 2 .1; elements Table 4 (dash 12d, gap 3d); applications in Annex D
- 02.2: ISO 128-2:2020, Table 1 no. 02 (dashed), Table 2 .2; elements Table 4 (dash 12d, gap 3d); applications in Annex D
- 04.1: ISO 128-2:2020, Table 1 no. 04 (long-dashed dotted), Table 2 .1; elements Table 4 (long dash ~24d, gap 3d, dot <= d); applications in Annex D
- 04.2: ISO 128-2:2020, Table 1 no. 04 (long-dashed dotted), Table 2 .2; elements Table 4; applications in Annex D
- 05.1: ISO 128-2:2020, Table 1 no. 05 (long-dashed double-dotted), Table 2 .1; elements Table 4; applications in Annex D
Source and verification
- Standard
- ISO 128-2:2020 Technical product documentation (TPD) - General principles of representation - Part 2: Basic conventions for lines (ISO 128-2:2022 is a minor revision with the same tables)
- Verification
- not recorded in this data file
- Data file
library/line-types/iso-128-2.json
Values that could not be checked against the standard are left out and listed in docs/to-verify.md. Check the standard itself before you rely on a value for production, and report any mistake on GitHub. to-verify.md · Issues