Revit Architecture: Unitsosaurus Success or Failure

Model quality or qualities; or lack(s) thereof(s) are, in my opinion, based on correct geometry. Seeing countless BAD BIM, I am forced (LOL) to implore individuals (CAD and BIM “Managers”), projects, teams, AND finally firms that can’t get simple geometry straight... literally cannot model straight; to get it right already!!!

I am again posting this in a yearly attempt at getting buy-in to REALITY!!!

Why? The overwhelming and f rankly unprofessional mediocrity (a majority, like 95%) of AEC production (not modeling straight or correctly) is rampant in Revit® and every other BIM platform, so don’t think you’re OK Bentley, Graphisoft, et al. If your units are set up like Figure 1, then you are dismissed lol... Seriously ;) ...Everyone else, be scared and read on.

Figure 1: Image illustrating proper overall units

Okay, so since you are still here, I hope this will clear up a few ideas or at least give a starting point for more research into quality, precision, and what it is we are doing in AECO.

If your Revit project template’s units (today we are talking Revit, but I do not care about the software: set Units as granular as possible) are NOT set as shown in Figure 1, and they are more like Figure 2, set your units up as I will explain. IMMEDIATELY after reading this. NO JOKE!!!

I will hold back on much more editorializations, except to say that if you disagree with any of these concepts, please contact me on twitter @JayZallan and try your best! I dare you. For what its worth, I have geometry, floating-point precision, and quality in my corner.

Do you have any “Wall is slightly off axis”? Or worse yet, “Line is slightly off axis” warnings? “Slightly Off Axis” warnings are directly related to mediocre, or just plain bad, modeling. If you use any CAD drawing in your process, you will most likely have found these files are some of the causal factors (and if you are still reading, have ignored such Revit warnings). Regardless, a BIM shall be correct, and not approximated or rounded to the 1/8” (or whatever contractual precision’s been set) until the dirt hits the shovel (AKA: during construction). Both bad modeling, and bad CAD, create bad BIM. Which is costing your firm time and money.

So here we go—only tech f rom here on out.

Do not use the following setup.

Figure 2: Image illustrating possibly the most unprofessional and unintelligent setup of units possible

Set up Dimensions to respect Project Units.

I am not saying leave dimensions that report to the x/256 of an inch.

What I am saying is:


Fix the model, do not override dimensions.

I do create one Dimension Type that does not use Project Units and rounds to 1/8” (if that is your contractual obligation).

Make this rounded dimension red.

Rarely use this for individual dimensions, where geometry dictates or when the site dictates odd angles, etc.

Never use these for dimension strings. FIX THE MODEL in that case!


Setting up Revit units correctly and professionally.

Type “UN”


Click the button under the “Format” heading for “Length” and set up as follows:

YES, 1/256”.

“Suppress 0 feet” is cool to uncheck if you are into that sort of old-timey thing. I like it personally, but still, I do not usually use it.

Digit grouping makes numbers look as we like in the USA... commas and all.

“Suppress spaces” is ok to check if you are into that sort of thing.

Please understand that this comment goes for all following Units’ dialogs as well, as I am not into suppressing spaces.

Figure 3: Image illustrating proper “Length” units


Click the button under the “Format” heading for “Area” and set up as follows:

Two decimal places.

Suppress trailing 0s.

This is key. One will only see extra 0s if there are numbers other than 0 to the right of the decimal (0s are visible in Temporary Dimensions and when OBJs are selected, but that is how it should be. Let me see reality!)

All the rest as shown:

Figure 4: Image illustrating proper “Area” units


Click the button under the “Format” heading for “Volume” and set up as follows:

Note: one may want to get more granular with this if refined calculations are desired.

Figure 5: Image illustrating proper “Volume” units


The following settings are even more important than the length settings, as we geolocate our models and need this granularity and quality. (Full Stop)

“Rounding” set to “Custom”.

Place cursor between the 0 and 1, to the right of the decimal point.

Enter “0” ten (10) times.

Just do it, you will thank me when Shared Coordinates don’t blow up anymore (as if).

Remember, the trailing 0s will only show up when the geometry is... well, let’s just say “probably needs work” (at best) and “is totally a joke for someone who calls themselves professional” (at worst).

Figure 6: Image illustrating proper “Angle” units


Settings are all in the following images. There are not many comments until “Time.”

Figure 7: Image illustrating proper “Slope” units. (Yeah, you can set them up for Rise/12, etc.… these are often modified to satisfy municipalities, outside jurisdictions, etc.)

Figure 8: Image illustrating proper “Currency” units (add the dollar sign!) I like to set it up like money (since that is what this unit is lol…) so I let the trailing 0s show proudly.

Figure 9: Image illustrating proper “Mass Density” units. The next time I use these will be the first, so if there are any mass density experts reading this, please let me know if there are better setups


Back in Revit© 2020 Time & Speed were added, and are going to allow a lot of future capabilities and I am looking forward to it!

Currently used in the new (and one day to be working properly) Exiting Path tools, with more potential functionality and workflows, beyond exiting alone for the creative masterminds.

Figure 10: Image illustrating proper “Time” units

Figure 11: Image illustrating proper “Speed” units


Revit Units should look something like Figure 12, but if there are differences, a few things should (if not must) remain constant: Length and Angle must be as granular as allowed, whether in Revit, CAD, or any other software used to author BIMs or any portion therein. Set the Units granular and then draw and model to rational dimensions. PERIOD ;)

Figure 12: Image illustrating a properly set up Units dialog

Learn. Always. Push. Change. Inspire.

Art - Architecture - Technology - Creativity

With over 20 years of Architectural experience Jay B. Zallan enjoys a varied and diverse portfolio spanning high-end custom residential design, large mixed-use developments, major transportation and inf rastructure projects through most every large-scale project type. President of LARUG (Los Angeles Revit Users Group) and an Autodesk Implementation Certified Expert (ICE), Jay combines unique insights into the creative and business process of AECO with proven management, creativity, and project generating strategies. Enabling, empowering, and inspiring teams to realize their own dreams and potentials beyond limitations (whether real or perceived).

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