Revit 2024 – Room Dimensions on Tag tip – Part 1

By Dennis Collin

I recently had a question whether a Room tag in Revit could show the length and width of a room as well as area, name, and number etc. Depending upon the complexity of the room this can be done with a simple formula in the Room tag family.

Within the Room Tag family, add a label referencing Room Name, Number and Area if required, then add a calculated parameter for Length.

Where:

• P-Perimeter
• A-Area
• l-Length
• w-Width

The length parameter will be a conditional if statement which will divide the perimeter length by 4 if the room is square, where the walls have equal length, otherwise the formula will calculate 2 different values for the length and the width using the Area and Perimeter values.

The formula for the length parameter should read: if(Area = (Perimeter / 4) ^ 2, Perimeter / 4, ((Perimeter / 2) - sqrt((Perimeter / 2) ^ 2 - 4 * Area)) / 2)

Create another calculated parameter for the width. This one is a little simpler as it just divides the measured area by the width.

The Width formula should read: Length/Area

Then once complete, load into the project and tag the rooms as desired. A limitation for this method is that it only works for rooms of 4 sides. For irregular shaped rooms, incorrect values will be displayed on the tag. Also, in some instances the longest value, usually considered the length, gets shown as the width which is not always what is expected.

To get around these problems, users will need to access the power of the API (programming environment) or by utilising Dynamo scripting. The latter process I will cover in a future post.