2.5Dimensioning: dimension styles, linear/angular/radius dimensioning & leaders
Dimensioning gives the drawing its technical value: it indicates the real dimensions and enables manufacturing or construction. AutoCAD can place every type of dimension: linear (horizontal/vertical), aligned, angular, radius and diameter, baseline and continued dimensions… Dimensions are generally associative: they update if the geometry changes.
The key to clean, standardized dimensions is the dimension style (DIMSTYLE): it defines the appearance of ALL the elements (arrows, text, extension lines, units, tolerances…) consistently, according to a standard (ISO, ANSI…). You complete it with multileaders (MULTILEADER) for arrowed annotations. Careful, standard-compliant dimensioning is what makes a plan usable by a workshop or a construction site.
Section vocabulary
- Dimensioning
- Indication of the real dimensions on a drawing (lengths, angles, radii, diameters).
- Dimension style (DIMSTYLE)
- Global setting of the dimensions' appearance (arrows, text, units, tolerances…), according to a standard.
- Linear / aligned dimension
- Linear: horizontal or vertical measurement. Aligned: parallel to the dimensioned object.
- Associative dimension
- Dimension linked to the geometry: it updates automatically if the object is modified.
- Multileader (MULTILEADER)
- Arrowed annotation linking text to a point in the drawing (callouts, notes).
What controls the appearance of all the dimensions?
In practice — Dimensioning a drawing according to a standard
- Create or choose a dimension style (DIMSTYLE) compliant with a standard (ISO), and set arrows, text and units.
- Place linear dimensions (horizontal/vertical) and aligned dimensions on a drawing, snapping to the endpoints.
- Add radius/diameter dimensions on circles and arcs, and an angular dimension.
- Check associativity: modify the geometry and see the dimensions update; add a multileader for a note.
Key points to remember
- Dimensioning gives the drawing its technical value (real dimensions).
- The dimension style (DIMSTYLE) controls the appearance of every dimension, according to a standard.
- Types: linear, aligned, angular, radius, diameter, baseline, continued.
- Associative dimensions update with the geometry.
Frequently asked questions
My dimensions are tiny or gigantic, why?
It's a question of the dimension style scale relative to the size of the drawing. Dimension elements (text, arrows) have a fixed size that must be adapted to the print scale: on a large drawing dimensioned at 1:100, you need a proportional dimension scale factor (DIMSCALE), or use annotative dimensions that handle this automatically. Setting this scale factor is the classic dimensioning adjustment.
Should I dimension in model space or paper space?
Both approaches exist. Dimensioning in model space (with annotative dimensions or an adapted DIMSCALE) is very common and robust. Dimensioning in paper space (on the layout) gives a controlled dimension size when printing, but links the dimensions to the viewport. Annotative dimensions are the recommended modern solution: they display at the right size depending on the scale. We go deeper into layouts at level 3.