Reference · Drawings
DIN drawing standards: a one-page cheat sheet
The drawing rules behind Unit 06 of the course, on one page: sheet sizes, scales, lines, projection, sections, dimensions, general tolerances, fits and surface texture. Keep it open next to Inventor when you prepare a drawing.
Reading 7 minBy Smit A, CAD instructorUpdated 28 October 2026
Which standards apply
A drawing marked “DIN” today follows international ISO rules: Germany adopts most of them as DIN, DIN EN or DIN ISO standards. Inventor’s Standard (DIN) templates are set up for them, which is why this course uses them from Lesson 1.
| Topic | Standard | What it covers |
|---|---|---|
| Sheet sizes and layout | ISO 5457 (sizes from ISO 216) | A-series sheets, borders and the drawing frame |
| Title block | ISO 7200 | The data fields: title, drawing number, owner, creator, approver, date, revision |
| Scales | ISO 5455 | Recommended enlargement and reduction scales |
| Lines | ISO 128-2 | Line types, line widths and what each is used for |
| Views, sections and cuts | ISO 128-3 | Arranging views, section views and hatching |
| Projection methods | ISO 5456-2 | First-angle and third-angle orthographic projection |
| Dimensioning | ISO 129-1 | How dimensions and tolerances are written |
| General tolerances | ISO 2768-1 | Default tolerances for dimensions with no tolerance of their own |
| Limits and fits | ISO 286-1 and ISO 286-2 | Tolerance grades and fits such as H7/g6 |
| Threads | ISO 6410-1 | How threads are drawn and noted |
| Surface texture | ISO 21920-1 | Surface texture symbols (it replaced ISO 1302) |
Sheet sizes and the frame
Each A-size sheet is half the one before it, with sides in the ratio 1 : √2. A4 is normally used upright (portrait) and the larger sizes on their side (landscape). The drawing frame leaves a 20 mm margin on the left for filing and 10 mm on the other edges, and the title block sits in the bottom-right corner.
| Size | Width × height (mm) | Typical use |
|---|---|---|
| A4 | 210 × 297 | Single parts like the ones in this course |
| A3 | 420 × 297 | Larger parts, or parts with several views and a section |
| A2 | 594 × 420 | Small assemblies |
| A1 | 841 × 594 | Assemblies and layouts |
| A0 | 1189 × 841 | Large assemblies and general arrangements |
In Lesson 11 you set up an A4 sheet with the DIN title block before placing any views.
Scales
Choose the largest scale that fits the views on the sheet with room for dimensions. Whatever the scale, the dimensions always show the real size of the part. The main scale goes in the title block; a detail view states its own scale next to its label.
| Kind | Recommended scales |
|---|---|
| Enlargement | 50:1 · 20:1 · 10:1 · 5:1 · 2:1 |
| Full size | 1:1 |
| Reduction | 1:2 · 1:5 · 1:10 · 1:20 · 1:50 · 1:100 · 1:200 |
Line types
Two line widths do most of the work: wide lines are twice as thick as narrow lines. Common pairs are 0.5 mm with 0.25 mm, or 0.7 mm with 0.35 mm. Inventor’s DIN styles apply the right type and width automatically; the table helps you read a drawing and spot mistakes.
| Line | Used for |
|---|---|
| Continuous wide | Visible edges and outlines |
| Continuous narrow | Dimension and extension lines, leaders, hatching, short centrelines, thread roots |
| Continuous narrow, freehand or zigzag | The edge of a partial view, a break or a break-out |
| Dashed narrow | Hidden edges and outlines |
| Long-dash dotted narrow | Centrelines, lines of symmetry and pitch circles |
| Long-dash dotted narrow, wide at the ends and corners | Cutting planes for section views |
| Long-dash dotted wide | Surfaces with a special requirement, such as a heat-treated area |
| Long-dash double-dotted narrow | Adjacent parts, extreme positions of moving parts, outlines before forming |
First-angle projection
Europe uses first-angle projection. Imagine the part sitting in front of the sheet and each view projected through it onto the paper behind: the view from above lands below the front view, and the view from the left lands to the right of the front view. The United States mostly uses third-angle projection, where both are the other way round.
Because the two methods put the same views in opposite places, every drawing states its method with the projection symbol, a small truncated cone, in or next to the title block. If you receive a drawing from abroad, check the symbol before you read the views.
Section views
- The cutting plane is drawn as a long-dash dotted narrow line, wide at the ends and corners, with arrows showing the viewing direction and a capital letter at each end.
- The section view carries the same letters, for example A-A.
- Cut material is hatched with continuous narrow lines, usually at 45°. The same part uses the same hatch in every view; neighbouring parts use a different direction or spacing.
- Shafts, bolts, screws, pins, keys, ribs and webs are not hatched when the cut runs along their length.
You create section A-A in Lesson 11.
Dimensioning
- All dimensions are in millimetres and are written without the unit.
- Dimension each feature once, in the view where it is clearest. Avoid dimensioning to hidden lines.
- Measure from functional surfaces (the faces that locate the part), not from wherever is convenient on screen.
- Text sits above the dimension line and reads from the bottom or the right-hand side of the sheet.
- Common symbols: Ø diameter, R radius, SØ and SR for spheres, □ square. A chamfer is written as, for example, 2 × 45°.
- Threads: M10 means the standard coarse pitch (1.5 mm); M10 × 1.25 states a fine pitch. Tolerance class 6H is usual for internal threads and 6g for external ones.
In Inventor, use hole and thread notes rather than typed text: they read the size from the feature and stay correct if the model changes. Lesson 12 covers center marks, notes and DIN dimension styles.
General tolerances (ISO 2768-1)
A dimension without its own tolerance is still not exact: it gets the general tolerance named in the title block. Class m (medium) is the usual choice for machined parts. You will often see ISO 2768-mK: m is the class from this table and K a class for general geometric tolerances from Part 2 of the standard.
Linear dimensions, permitted deviation in mm:
| Nominal size (mm) | f (fine) | m (medium) | c (coarse) | v (very coarse) |
|---|---|---|---|---|
| 0.5 up to 3 | ±0.05 | ±0.1 | ±0.2 | — |
| over 3 up to 6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| over 6 up to 30 | ±0.1 | ±0.2 | ±0.5 | ±1 |
| over 30 up to 120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| over 120 up to 400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| over 400 up to 1000 | ±0.3 | ±0.8 | ±2 | ±4 |
| over 1000 up to 2000 | ±0.5 | ±1.2 | ±3 | ±6 |
| over 2000 up to 4000 | — | ±2 | ±4 | ±8 |
External radii and chamfer heights, in mm:
| Nominal size (mm) | f and m | c and v |
|---|---|---|
| 0.5 up to 3 | ±0.2 | ±0.4 |
| over 3 up to 6 | ±0.5 | ±1 |
| over 6 | ±1 | ±2 |
Angles, by the length of the shorter side:
| Shorter side (mm) | f and m | c | v |
|---|---|---|---|
| up to 10 | ±1° | ±1°30′ | ±3° |
| over 10 up to 50 | ±0°30′ | ±1° | ±2° |
| over 50 up to 120 | ±0°20′ | ±0°30′ | ±1° |
| over 120 up to 400 | ±0°10′ | ±0°15′ | ±0°30′ |
| over 400 | ±0°5′ | ±0°10′ | ±0°20′ |
Fits (ISO 286)
Where a shaft runs in a hole, a general tolerance is not enough: you choose a fit. With the hole-basis system the hole is H (its lower limit is the nominal size) and the shaft letter sets how tight the pair is. The table shows the limits for a Ø20 mm pair.
| Fit | Type | Hole Ø20 (mm) | Shaft Ø20 (mm) | Typical use |
|---|---|---|---|---|
| H8/f7 | Clearance, running | H8: +0.033 / 0 | f7: −0.020 / −0.041 | Shafts turning in plain bearings |
| H7/g6 | Clearance, sliding | H7: +0.021 / 0 | g6: −0.007 / −0.020 | Parts that slide or turn with little play |
| H7/h6 | Clearance, locating | H7: +0.021 / 0 | h6: 0 / −0.013 | Parts assembled by hand that must locate accurately |
| H7/k6 | Transition | H7: +0.021 / 0 | k6: +0.015 / +0.002 | Accurate location; may need light pressing |
| H7/n6 | Transition, tight | H7: +0.021 / 0 | n6: +0.028 / +0.015 | Tighter location, pressed into place |
| H7/p6 | Interference | H7: +0.021 / 0 | p6: +0.035 / +0.022 | Press fits, such as a bush in a housing |
In Lesson 10 you use Measure to check the clearance between parts in an assembly.
Surface texture
The basic tick-shaped symbol means “this surface has a texture requirement”. A bar across it means material must be removed (machined); a circle in it means material must not be removed. The value next to it is usually Ra in micrometres. As a rough guide: Ra 6.3 for general machining, Ra 3.2 for a good machined finish, Ra 1.6 for fine machining, and Ra 0.8 or below for bearing seats and sealing faces.
Specify the roughest finish that still works: every step finer costs more machining time.
Title block
ISO 7200 defines the fields a title block can hold. On a student drawing, check at least these: title, drawing number, your name as creator, date, scale, sheet size, projection symbol, general tolerance (for example ISO 2768-m), material and revision. Inventor’s DIN title block fills several of them from the file’s iProperties, so set those before you print.
Before you print
- Sheet size and orientation suit the views, and the title block is complete.
- The scale in the title block matches the views; detail views show their own scale.
- The projection symbol shows first-angle projection.
- Every hole has a center mark and is dimensioned from its centre.
- Hole and thread sizes come from notes, not typed text.
- Each dimension appears once; none point to hidden lines.
- Section letters match between the cutting plane and the view.
- Hidden lines appear only where they help.
A study summary for students, not a replacement for the standards themselves; always use the current edition your school or company specifies. Spotted an error? Tell us.