Roof slopes, stairs, braces, skewed walls on a plan: any edge that is neither horizontal nor vertical gets the wrong number from an ordinary linear dimension. An aligned dimension in AutoCAD measures along the edge itself, so the value is the true length rather than a projection.
This article covers DIMALIGNED, the Rotated option of DIMLINEAR and the Oblique option of DIMEDIT in AutoCAD 2027, using the acadiso.dwt template. Every value is read back from the dimension object. A quick comparison of all dimension commands is in the other dimension commands. For dimensioning taught properly, the Institute runs an AutoCAD course for construction.
The DIMALIGNED command and its relatives
| Command | Alias | Measures | Menu |
|---|---|---|---|
DIMALIGNED | DAL | Length along the line through two points | Dimension → Aligned |
DIMLINEAR | DLI | Horizontal, vertical, or at a given angle | Dimension → Linear |
DIMEDIT | DED | Slants extension lines, rotates text | Dimension → Align Text |
On the ribbon, DIMALIGNED and DIMLINEAR sit on the Annotate tab, Dimensions panel, Linear drop-down; DIMEDIT Oblique has its own button in the same panel. Locations and aliases come from the 2027 acad.cuix and acad.pgp files. The Autodesk documentation on DIMALIGNED describes the dimaligned command as creating a linear dimension aligned with its two origin points.
Step by step
Type DAL and the 2027 release asks:
| Step | The prompt | What you do |
|---|---|---|
| 1 | Specify first extension line origin or <select object>: | Pick the first point, or press Enter to select a whole line |
| 2 | Specify second extension line origin: (after a point) or Select object to dimension: (after Enter) | Pick the second point, or click the line |
| 3 | Specify dimension line location or [Mtext/Text/Angle]: | Place the dimension line |
On a right triangle with legs 3000 and 4000, DIMALIGNED on the hypotenuse gives 5000. DIMLINEAR on the same two points gives 3000, because it measures the projection. Pressing Enter at step 1 and clicking the line also gives 5000. The sloping segment of a polyline, 2000 by 1500, selected the same way gives 2500, with no need to explode the polyline.
The text of an aligned dimension runs parallel to the edge: 30° for a line at 30°, 36.87° for the polyline segment. You do not set this angle; it comes from the two points. If you want the text at a fixed angle instead, the Angle option at step 3 accepts one, just as it does for other dimension commands.
Typed points or a picked line: the biggest difference
Both routes give the same number at first, but not later. When the two points are typed as bare coordinates, without snapping to the line, the 2027 release says straight away:
Non-associative dimension created.A non-associative dimension is attached to nothing. Stretch the hypotenuse from 5000 to 10000 and read the dimensions again.
| How the points were given | AutoCAD says | After stretching to 10000 |
|---|---|---|
| Bare typed coordinates | Non-associative dimension created. | still 5000 |
The same coordinates with _endp | Nothing | 10000 |
| Enter, then pick the line | Nothing | 10000 |
The culprit is not typing coordinates but points that do not snap to the geometry. When picking with the mouse, keep the Endpoint object snap on; or press Enter and select the line. Object snaps are covered in object snaps in AutoCAD. The message Non-associative dimension created. is your cue to undo and redo at once.
Rotated dimension: the distance between sloping parallels
Two parallel walls run at 30° and you need the distance between them. DIMALIGNED only gets it if your two points happen to be exactly square to the walls. The reliable tool is a rotated dimension: DIMLINEAR with the Rotated option.
| Step | The prompt | What you do |
|---|---|---|
| 1, 2 | The two origin prompts | Pick a point on each line |
| 3 | Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: | Type R |
| 4 | Specify angle of dimension line <0>: | Type the angle square to the lines: 30 + 90 = 120 |
| 5 | The placement prompt | Place the dimension |
With the lines 600 apart, the 120° rotated dimension shows 600; the object is a RotatedDimension with its dimension-line angle stored as 120°. Its strength is that the two points need not be square to each other. Pick one near the middle of the first line and one far along the second:
| Command, same two offset points | Value |
|---|---|
DIMLINEAR → R → 120 | 600, the true distance between the lines |
DIMALIGNED | 1268.56, the diagonal between the two points |
The rotated dimension projects the two points onto the 120° direction, so it returns 600 however far apart you pick. DIMALIGNED measures straight between the points and is wrong as soon as they are offset.
Oblique dimension for isometric drawings: DIMEDIT Oblique
Isometric drawings need a different style: extension lines parallel to an axis of the drawing rather than square to the edge. That is an oblique dimension, made with DIMEDIT, option Oblique, on an existing dimension.
| Step | The prompt | What you do |
|---|---|---|
| 1 | Enter type of dimension editing [Home/New/Rotate/Oblique] <Home>: | Type O |
| 2 | Select objects: | Select the dimension, Enter |
| 3 | Enter obliquing angle (press ENTER for none): | Type the extension-line angle |
A line at 30°, 4000 long, dimensioned with DIMALIGNED has extension lines at 120°, square to the line. Different angles typed, and the extension lines read back:
| Typed angle | Extension lines | Value |
|---|---|---|
90 | Vertical, 90° | 4000 |
150 | 150° | 4000 |
30 | Unchanged, since 30° is parallel to the dimension line itself | 4000 |
| Enter after setting 150 | Still 150°, not restored | 4000 |
The angle is absolute, measured from the X axis, not an offset from the current slant. The value always stays 4000. Enter does not restore square extension lines: to go back, type the square angle again, here 120.
Choosing a command for a sloping edge
| You need | Use | Example |
|---|---|---|
| The true length of a sloping edge | DIMALIGNED | 3-4-5 hypotenuse gives 5000 |
| The distance between sloping parallel lines | DIMLINEAR → Rotated | Two walls at 30°, 600 apart |
| The horizontal or vertical projection of a sloping edge | DIMLINEAR | 3-4-5 hypotenuse gives 3000 or 4000 |
| A dimension on an isometric drawing | DIMALIGNED, then DIMEDIT → Oblique | Vertical extension lines, angle 90 |
All four should be created from snapped points or picked objects, so the values follow the geometry when the drawing is revised.
A worked order for a skewed plan
Putting the results together gives a safe order for a plan with a wall set at 30° to the grid:
- Check that the
Endpointobject snap is on before you start dimensioning, or plan to press Enter and pick lines. - Dimension the length of each skewed wall with
DAL, picking the wall line itself. - Dimension the wall thickness with
DLI,R, and the angle square to the wall, here 120. Pick one point on each face; they need not be opposite each other. - Watch the command line. If it ever says
Non-associative dimension created., typeUand repeat with snapped points. - If a skewed wall is drawn as part of a polyline, dimension its segment with
DAL, Enter, and a click on the segment; it measures that segment alone, 2500 for a 2000 by 1500 run.
With this order, the lengths stay correct when walls are lengthened, because every dimension is attached to the geometry. The only dimensions that can drift are the ones that printed the non-associative message, and step 4 removes them before they reach the drawing set.
Three things often repeated that are not true
| Often repeated | What holds on the 2027 release |
|---|---|
| Typed points and picked lines are equivalent | Bare typed points make a non-associative dimension that keeps its old value when the line changes |
| Oblique takes an offset from the current slant | The angle is absolute, from the X axis |
| Enter at the Oblique prompt restores the original lines | The extension lines keep the angle last set |
Frequently asked questions
Which command gives an aligned dimension in AutoCAD?
DIMALIGNED, alias DAL. It measures along the line through the two points, so a 3-4-5 hypotenuse gives 5000.
Why does my sloping edge show a smaller number?
You used DIMLINEAR, which measures the projection. Use DIMALIGNED.
How do I dimension the distance between two sloping parallel lines?
DIMLINEAR, type R, enter the angle square to the lines, then place the dimension.
How do I make isometric-style dimensions?
Dimension with DIMALIGNED, then DIMEDIT → O, select the dimension and type the extension-line angle, for example 90.
Why did the value not change when I stretched the line?
The dimension was made from bare typed points and is not associative. Recreate it by selecting the line or by picking snapped points.
Can I dimension a polyline segment this way?
Yes. Press Enter at the first prompt and click the sloping segment.