In this guide
If your numbers and notes come out the wrong size when you plot, the fix almost always comes down to one number: the drawing scale factor. Below is a quick calculator, a ready-to-use scale chart, and short answers to the most common dimension-text problems.
The short answer: Model-space text height is your desired plotted height multiplied by the scale factor. For dimensions, set DIMSCALE to that same factor.
Model text height = Plotted height × Scale factor
Text Height & Dimension Scale Calculator
Modern method: instead of a fixed factor, you can set the style to Annotative and add this scale as an annotation scale — then keep text/dim height at the plotted value (2.5) and let CAD handle the rest.
AutoCAD Text Height Chart
This table gives the model-space height to type so that text plots at the size in each column. Values are plotted height × scale factor.
| Scale | 2.5 mm | 3.5 mm | 5 mm | Factor |
|---|---|---|---|---|
| 1:1 | 2.5 | 3.5 | 5 | 1 |
| 1:2 | 5 | 7 | 10 | 2 |
| 1:4 | 10 | 14 | 20 | 4 |
| 1:5 | 12.5 | 17.5 | 25 | 5 |
| 1:10 | 25 | 35 | 50 | 10 |
| 1:20 | 50 | 70 | 100 | 20 |
| 1:50 | 125 | 175 | 250 | 50 |
| 1:100 | 250 | 350 | 500 | 100 |
| 1:200 | 500 | 700 | 1000 | 200 |
| Scale | 3/32″ | 1/8″ | 3/16″ | Factor |
|---|---|---|---|---|
| 1″=1′ | 1.125 | 1.5 | 2.25 | 12 |
| 3/4″=1′ | 1.5 | 2 | 3 | 16 |
| 1/2″=1′ | 2.25 | 3 | 4.5 | 24 |
| 1/4″=1′ | 4.5 | 6 | 9 | 48 |
| 1/8″=1′ | 9 | 12 | 18 | 96 |
AutoCAD Text Height for 1:4 Scale
At 1:4, the scale factor is 4, so multiply your plotted text height by 4 in model space:
- A 2.5 mm note → 10 mm in model space
- A 3.5 mm note → 14 mm
- A 5 mm note → 20 mm
Set DIMSCALE to 4 so dimensions match, or pick 1:4 in the calculator above to confirm any height. The same logic works for every ratio — just swap 4 for your scale factor.
Why Is My AutoCAD Dimension Text Too Big or Too Small?
This is nearly always a DIMSCALE mismatch. DIMSCALE multiplies every size in the dimension style — including the text. If your text plots too big, DIMSCALE is higher than your drawing scale factor; too small means it’s lower.
- Type
DIMSCALEand set it to your scale factor (use the calculator above). - Type
UPDATE, then select the dimensions to apply it.
Why Is My AutoCAD Dimension Text Not Changing?
When the size won’t budge, one of three things is overriding you:
- The dimension style controls it, not the object. Editing one dimension’s properties may be ignored. Change it in
DIMSTYLE→ Modify → Text tab, then update. - The style is Annotative. Then
DIMSCALEis ignored on purpose — the displayed size is driven by the current annotation scale at the bottom of the screen, not by typing a value. - The text style has a fixed height (see below), which locks the value the dimension can use.
How to Change AutoCAD Dimension Text Size
- Run
DIMSTYLE(Dimension Style Manager). - Select your style → Modify → Text tab.
- Set Text height to your plotted height (e.g. 2.5 or 1/8″), and confirm
DIMSCALEon the Fit tab matches your scale factor.
For a quick one-off without opening the manager, the variables are DIMTXT (text height) and DIMSCALE (overall multiplier).
How to Unlock Text Height in AutoCAD
If you can’t set a text height because the box is greyed out, the text style has a fixed (non-zero) height, which locks it.
- Run
STYLEto open the Text Style Manager. - Select the style and set its Height to
0. - Now you can set the height per object — and your dimension style can drive it.
Quick command reference
What Is the Drawing Scale Factor?
The scale factor is how many times bigger real-world objects are than your plotted sheet. For a metric ratio 1:n, the factor is simply n — so 1:50 has a factor of 50. For an architectural scale, divide 12 by the inch value: 1/4″ = 1′-0″ is 12 ÷ 0.25 = 48. Because everything you draw lives at full size in model space, text and dimensions must be drawn that many times larger to plot at a readable size.
This is also why the annotative workflow exists: instead of memorising a factor per scale, you tag text and dimension styles as annotative and assign annotation scales, letting the software size them automatically across multiple viewports — a feature you’ll find in the full feature set of any modern DWG editor.
Same commands, any DWG editor
Worth knowing if you work across tools: these variables — DIMSCALE, DIMTXT, LTSCALE, PSLTSCALE — and the annotative scaling workflow are part of the standard DWG command set. They behave the same way in AutoCAD and in DWG-compatible CAD software like SmartCAD, so the chart and calculator above apply regardless of which one you’re running. If you’re weighing options, you can see how it compares or download a free 30-day trial.
