Dimensions in Revit – What you need to know

Accurate dimensions inside your Revit drawings are very important to ensure your project is built to your design. To accomplish this we can use different tools in Revit. Knowing what tools you can use and how they work will really help make your drawings easier to read and understand.

Good to know that the dimensions in Revit are based on a system-based family. This means that we can fully modify the look and feel of our dimensions.

In this article, I will explain the different types of dimensions tools that are available in Revit. When to use which tool and of course how you can customize your dimension styles.

Overview

Revit has multiple types of dimensions available. There are a total of nine different tools in the Annote tab > Dimension section. Dimensions are system-based families, which means that they are customizable.

1. Aligned
2. Linear
3. Angular
4. Radial
5. Diameter
6. Arc Length
7. Spot Elevation
8. Spot Coordinate
9. Spot Slope

Each type of dimension in Revit has its own usage. The most commonly used dimension is the Aligned dimension. Nonetheless, the features of each dimension type are quite similar to one another.

Dimension types in Revit

Aligned

Places dimension between parallel references and multiple points. Within the drawing area, the reference points will light up when you move over with your cursor. When elements are close to one another, press the tab button to cycle through them.

Linear

Places only horizontal or vertical dimensions, that will measure the distance between the reference points. This tool allows you only to align the dimensions on the horizontal or vertical axis in Revit.

Angular

Places dimension that will measure the angle between multiple references. This can only be used when there is a common intersection between them (not parallel).

Radial

Places dimension that will measure a radius of a curve. The most common use is the inner curve, but it can also be used for the outer or even on the centerline.

Diameter

Places dimension that will measure the diameter of a circle or arc. This tool can be used on the wall faces (inner and outer), or centerline.

Arc Length

Places dimensions that will measure the length of a curved element (walls, generic models, etc.) in Revit. This tool requires at least two intersecting references before it measures.

Spot Elevation

This tool will let you place the elevation of the selected point inside your drawing. Spot elevations can be drawn in plan views, elevations, and 3D views.

Spot Coordinate

This tool will let you place the coordinates of a selected point inside your drawing. The coordinates are displayed as Nort/South and East/West. The spot coordinate can be placed at elements such as walls, floors, etc.

Spot Slope

This tool will let you place the slope of a specific model element. Spot slopes can be drawn in plan views, elevations, and sections.

Placing a Dimension in Revit

The dimensions that we place in Revit, are permanent dimensions and will be visible inside the view you working at. However, there are also dimensions that are temporary, which I will explain more about later. So let’s first take a look at how to use the dimension. For the examples below, I am going to use the Aligned dimensions, but the principle is the same for all dimension types.

To place an Aligned dimension simply go to the Annote tab > choose Aligned or use the default shortcut DI, and notice that the options bar will pop up.

1. Open the Annotate tab
2. Click on Aligned or use the default shortcut DI > Options bar will show up

3. Choose references focus (Wall centerlines / Wall faces / Center of core / Faces of core).
4. Choose Individual References or Entire Walls

For now, we choose Wall faces with Individual References. Click on the (model element) references to create the dimension. After the last-clicked reference, make sure to finish the dimension line by clicking on the white space area.

Tip

Make sure to use the tab button to cycle through the references when using the cursor over elements, lines, etc.

Edit Witness Lines

After finishing the created dimension, it is possible to add or remove multiple segments by using the Edit Witness Lines in the Modify tab.

But the same also applies here: after the last-clicked reference to add or remove a segment, click on the white space to finish the dimension line.

Moving elements

Dimensions can also be used to move elements, lines, etc in Revit. To move an element with a dimension, you can use a permanent or temporary dimension.

Permanent dimension: click on the element you like to move, and notice that the element and permanent dimension will light up blue (by default). Click on the dimension value to change the dimension, and the element will move.

Temporary dimensions: with this method, you don’t have a dimension placed yet. But yet, it is still possible to do the same trick as written above. Click on the element you like to move and notice that the element will light up blue (by default) and a temporary dimension will appear. Click on the dimension value to change the dimension, and the element will move.

You can move the Witness Lines to other references by clicking on the dots (1) or dragging them. Another feature of the temporary dimensions in Revit is that you can make them permanent dimensions by clicking on the symbol below the dimension value (2).

Dimension Parameters

The Aligned dimension type in Revit has by far the most type parameters to care about. There are a total of 44 type parameters, with some depending on other choices (otherwise greyed out). Before we continue explaining them one by one, let’s split them up into groups.

• Graphics
• Text
• Primary Units
• Alternate Units
• Other

Graphics

This group contains a total of 22 type parameters to customize. The type parameters (by default) are not in the right order in my opinion. This makes it a little harder to understand what these parameters do. So I will try to group them as much as I can in this paragraph.

Dimension String Type

There are three types of string dimensions to choose from in Revit:

1. Continuous: measure multiple dimensions from reference to reference (segments).
2. Baseline: measure multiple dimensions from the same point of origin. Every measurement will be placed on a single line above or below each other (stacked).
3. Ordinate: measure multiple dimensions from the same point of origin. Every measurement will be placed on the same dimension line.

Dimension & witness lines parameters

The next parameters will help you to set the dimension and witness lines parameters.

Leader Type

This option lets you choose between a Line (1) or Arc (3). The leader will only be visible when you move the dimension value away from the line. This can be very handy if there are a few dimensions close to each other in your Revit model.

Make sure you check the Leader option in the options bar or Properties browser.

When you choose the line variant it is also possible to set the Shoulder Length (2) with a length value. The Show Leader When Text Moves parameter will let you choose Away From Origin Or Beyond Witness Lines. When you choose Away From Origin, the leader will immediately display when a text (value) is moved. The Beyond Witness Lines only display a leader when the text (value) crosses the path of the witness line of the dimension.

Line Weight

The Line Weight parameter sets a weight number that will designate the thickness of all dimension lines (extensions, tick marks, and leader included). The line weight can be set to a number of 1 to 16. To manage these line weights, check this article.

(Flipped) Dimension Line Extension

The Dimension Line Extension will extend the dimension line beyond the intersection of the witness line with a value you prefer. This will be visible for the first and last dimension segments.

The Flipped Dimension Line Extension will control the extent of the dimension line beyond a flipped arrow. This parameter can only be set if the Tick Mark parameter is set to an arrow style.

Witness Line Extension

The Witness Line Extension will control the extension of the witness line beyond the tick mark on the exterior side.

Witness Line Control

This parameter will let you choose between two options: Fixed to Dimension Line or Gap to Element.

Witness Line Length & Gap to Element

The Witness Line Length will become available when you choose Fixed to Dimension Line. The parameter will let you set a value to the length of all witness lines in the dimensions of your Revit model.

The Witness Line Gap to Element will become available when you choose Gap to Element. The parameter will let you set a value to the distance between the witness line and the elements being dimensioned.

If one of these two options does not fit your requirements, there is also an option to customize the witness lines, by dragging the outer dots (blue). In the example below you can see that it is also possible to drag the witness lines to the exterior side.

Color

The Color parameter will let you change the color of the whole dimension line, including the extensions, tick marks, leaders, and text.

Dimension Line Snap Distance

The Dimension Line Snap Distance parameter in Revit will set a fixed distance between two or more different dimension lines. The dimension lines will snap at the value you entered. This feature will aid you in stacking dimensions with even intervals. It is also possible to place them manually without using the snap feature.

Tick Mark parameters

A tick mark is a symbol displayed at the ends of a dimension line or to the leader. These tick marks can improve the readability of a drawing.

The tick mark symbols are called Arrowheads inside Revit. To create your own type follow the steps.

1. Open the Manage tab
2. Click on Additional Settings
3. Hover over Annotations
4. Click on Arrowheads > Type Properties menu will open

5. Create a new Type by duplicating an existing one and giving it a name.
6. Choose the Arrow Style, Tick Size, etc > press OK

The Arrow Style contains 8 different options to choose from.

• Diagonal
• Arrow
• Heavy end tick mark
• Dot
• Elevation Target
• Datum triangle
• Box
• Loop

These styles can be edited by the parameters below Arrow Style. For example, you can choose a Dot and make the tick fill with a region. Autodesk Revit does not yet have a feature to make a custom loadable arrowhead.

Leader Tick Mark

The Leader Tick Mark parameter allows you to set a tick mark to the tip of the leader, at the dimension line. Keep in mind that the leader will only be visible when you move the dimension value away from the line.

Tick Mark

With the Tick Mark (main parameter), you can set a tick mark style to the dimension witness lines. Without a Tick Mark, the dimensions look very plain.

Tick Mark Line Weight

The Thick Mark Line Weight will let you allow to set a line weight that designates the thickness of the tick mark itself. Using another tick mark than the diagonal will also set a thicker outline to the symbol.

Witness Line Tick Mark

The Witness Line Tick Mark designates the mark display at the tail of a witness line. This option can make the drawing very messy and is not used very regularly.

Interior Tick Mark & Display

The Interior Thick Mark will let you set a style to the inner witness lines. This option can be shown with two different variants: Dynamic and Always Show. Dynamic will always show the Tick Mark whenever possible, when it’s too small it will automatically show the Interior Thick Mark. When you want the interior tick mark to show up always, then put the display to Always Show.

Make sure to at least have three witness lines and the thick mark set to an arrow type to make the Interior Thick Mark show up.

The picture below will show some examples.

1. Interior Tick Mark: none, Interior Tick Mark Display: Dynamic
2. Interior Tick Mark: diagonal, Interior Tick Mark Display: Dynamic
3. Interior Tick Mark: diagonal, Interior Tick Mark Display: Always Show
4. Notice that when the space between the arrows is too small they will reverse automatically. If the space between multiple segments becomes too small it will fill with the designated Interior Tick Mark.

Centerline parameters

The centerline options will only appear when an instanced family or wall is dimensioned on its centerline. Centerline parameters exist of three types you can choose from or even mix them together to your needs.

• Centerline Symbol: you can select a symbol to show up on a dimensioned centerline. Revit has a default generic annotation family for that (℄), and it’s called M_Centreline.rfa. Besides that, it is also possible to create your custom symbol by using a generic annotation family.
• Centerline Pattern: this will change the pattern of the witness line that is dimensioned on a centerline. For example, the pattern can exist of dashes or dots (depending on scale).
• Centerline Tick Mark: choose a tick mark that will show at the end of the centerline of a dimension.

Text

This group contains a total of 12 type parameters to customize.

Width Factor

The Width Factor will define the elongation of the text string, in this case, the dimension value. With a value of 1.0, there is no elongation (default).

Basic text parameters

The following parameters are essential parameters to set to the text string.

• Underline: this will underline the permanent dimension value and text.
• Italic: this will apply italic formatting to the permanent dimension value and text.
• Bold: this will apply bold formatting to the permanent dimension value and text.
• Text Size: specify the text size of the permanent dimension value and text.
• Text Font: set a text font to the permanent dimension value and text. You can use the standard Microsoft fonts or install custom ones.

Text Offset

The Text Offset specifies the offset of the text and value from the dimension line.

Text Background

The Text Background has two options to choose from.

• Opaque: the text and value are surrounded by a white box that will overlap any geometry or text behind it, inside the view.
• Transparent: this does the opposite of opaque, it will remove the white box, and any geometry or text behind it will be visible, inside the view.

Read Convention

The Read Convention is used to specify the start position and direction of the dimension text and value. It affects the dimensions lines that are placed vertically. The most commonly used read convention worldwide is the Up, then left.

Text Location

The Text Location refers to where dimension text is placed related to the leader. There are two options to choose from and are only available when you choose Leader Type: Line.

• Inline: the text and leader will be placed on the same line.
• Above: the text will be placed above the leader line.

Suppress Spaces

The Suppress Spaces parameter will let you remove spaces between the dimension value and text as in a prefix and or suffix. This will only affect dimensions with a prefix and or suffix.

Show Opening Height

The Show Opening Height parameter will allow you to show the height of an instanced window, door, or any other family. The naming of the parameter is a bit confusing because it will only read out the built-in parameter: Height. The example below shows the height of the inner wooden frame, which is important for the window factory and is not the opening height of the window itself.

To trigger the opening height, place the dimensions on the references of any family that contains the height parameter. The height value will appear below the dimension value.

Primary Units

This group contains a total of 3 type parameters to customize.

Units Format

The Units Format will use the Project Units settings inside the Manage tab by default. But to override these settings you can use the parameter Units Format. Make sure you unmark the Use project settings to make other options available.

Dimension Prefix and Suffix

The Dimension Prefix and Suffix parameters can be added individually if you double-click on the value of a dimension segment (see here). Since Revit 2022 we can also set the Prefix and Suffix as a type parameter that shows up instantly at each dimension value. In the example below we use a plus-minus symbol (±).

Alternate Units

This group contains a total of 4 type parameters to customize.

Alternate Units (Format), Prefix, and Suffix

The Alternate Units are the same as Unit Formats but can be used as a secondary dimension value to make measurements easier to read to other users for example. Alternate Units have three options to choose from. For example, to indicate an Alternate Unit, you can use brackets in the prefix and suffix to make it more clear.

• None: Alternate Units will not be displayed.
• Right: Alternate Units will be displayed in a line on the right side of the primary unit.
• Below: Alternate Units will be displayed below the primary value unit.

Other

This group contains a total of 3 type parameters to customize.

Equality parameters

The Equality parameters exist of three types. These equalities parameters are only visible when you have multiple dimension segments. After you placed the dimensions, click on the dimension and the EQ button will appear above. After you click on the Toggle Dimension Equality, the entities that are dimensioned will move and the text: EQ appears.

Equality Text

The Equality Text parameter specifies the text symbol to be used when the equality constraints are toggled on. By default, Revit uses the text EQ, but this can be changed to anything you like.

Equality Formula

With the Equality Formula, you can show up different values and even combine them with a prefix and suffix. you can choose from four built-in parameters.

• Length of Segment
• Number of Segments
• Number of Witness Lines
• Total Length

For example, if you combine a Number of Segments [Suffix: *], Length of Segment [Suffix: =], and Total Length. The outcome looks like the image below.

Equality Witness Display

To finalize the style of the Equality Witness Display, there are three options to choose from.

1. Tick and Line: this will display the interior witness line that is set in the type properties.
2. Tick only: this will display the tick mark but without the interior witness lines.
3. Hide: the interior witness lines and tick mark do not display.

Nonetheless, the Equality Text or Formula type parameters are only visible if you are setting the right instance parameter to the dimension line.

1. Click on the dimension line
2. Inside the Properties Browser go to Equality Display parameter
3. Choose Value, Equality Text, or Equality Formula

Additional Dimension features in Revit

Now that you have read everything about the different type parameters of the dimensions in Revit, there are still some additional dimension features that are somewhat hidden.

Auto dimension

Revit has a feature to auto-dimension an entire wall at once without the interference of third-party software. The feature has its own options to set up and includes Openings (centers or Widths), Intersecting Walls, and Intersecting Grids. Before you place an Aligned Dimension check the Options Bar for settings.

1. Pick Entire Walls
2. Open the Options panel inside the Options Bar > Auto Dimension Options menu will open
3. Select references which need to be dimensioned

4. Click on the wall you want to dimension > Click on the white space area to finish the dimension line

Set text

As you read before, it is possible to add text to your dimension value by double-clicking on it. The Text Fields you can choose from are Prefix, Suffix, Above, and Below. The overrides can vary for each segment if that is needed. The Prefix and Suffix can also be permanent by setting up the type parameter (only available since Revit 2022).

For a practical and creative way of using the text override, you can read the article: How to Calculate Brickwork Dimensions Automatically in Revit

Dimension constraints

As you maybe noticed before, each segment of the dimension will show a lock symbol. When you click this symbol the lock will close and that will create a constraint. The constraint will lock elements, reference planes, etc. together that are dimensioned. When you move one of the elements the other will move also.

The constraints are really useful when creating families with reference planes. Using constraints inside your project will be less recommended because it will cause a lot of warnings when you are using them wrong. Besides that, it will also slow down the performance of Revit due to constantly calculating when moving objects.

Delete segment from dimension

In Revit, it is possible to delete a segment from a multi-segment dimension. When you made a mistake, for example, you can remove segments by editing the witness lines, or simply remove a whole segment.

To do this hover over the segment and press the tab button. When the segment is highlighted (blue by default), click on the segment and press delete.

Wrapping up

There are nine different types of dimensions you can choose from in Revit. The most commonly used dimension is the Aligned Dimension which has the most type parameters to take care of. The parameters can be used individually to create a dimension style to your needs.

Always make sure that your dimensions are well readable on both screen and paper. Ask the people that are going to work with your model if it’s clear enough for them, or what can be improved.

I hope this article helped you to understand the different dimension type parameters, and how to create your dimension style in Revit. If you have any questions, just drop a comment below.