Overview

Every project is different, and there is no exact formula for keeping a project file size down. The listed items below are generally what to check and start with in order to reduce file size.

File Size ~ Performance

Roughly speaking, file size = performance, as the larger the file, the longer it will take to run, open, sort through its database, etc. So if you are experiencing revit file lag, generally the first step is to try and reduce file size.

Quality Computer Caveat

As a caveat, quality computer gear is required. Unfortunately Revit is a bloated program and Autodesk has done virtually nothing to help with this problem. So with the size of the files, you are unable to run larger revit files (500mb+) on mid-range laptops efficiently. It’s possible (and keeps getting easier with more advancements in computing), but you will end up reducing your multi-tasking ability and things are bound to slow down a bit.

Most Important — Understand… File size is going to increase.

There is a lot of information being put into a database that is going to increase the size no matter what you do. The main goal with Revit isn’t to keep the file small, but to have someone actively monitoring the file so it doesn’t get bigger than necessary. This person, (BIM Coordinator) is keeping tabs on the file and progress so that things won’t get out of control. Basically, the idea is to plan ahead to minimize issues down the road.+

Strategies to Reduce File Size & Increase Performance

1. Purge – As much as possible

Purge and get rid of any unused families, items, etc. This is number one on the list since it’s the easiest, but also most impactful to file size.
Purge is also the most potentially damaging… types you wanted to keep, or different families loaded in for use in the future will be removed without the proper precautions.
The purge command does not remove everything.

2. Areas & Rooms – Remove manually

These don’t get removed through purge. Helpful to create a schedule to view all unplaced areas (for each area scheme) and delete all unplaced areas.
Repeat for Rooms within the model.
Delete unused Area Schemes as well if possible. This will also delete the area plans associated with the area scheme. This has a large impact on the model because it deletes views (area plans), areas, area boundary lines, as well as other items that are on view specific to the areas.

3. Walls should not extend through multiple levels

Walls extending through multiple levels can cause relationship issues that confuse the program. Only utilize this sparingly. This strategy is typically used for exterior walls or for core walls. Keep it limited to these applications and limit the amount of hosted items.
If needing to host items, such as fire alarms or lighting to a core wall, consider hosting them to a reference plane instead of the wall.
Yes, this is from Autodesk’s mouth specifically and a crazy thing to say is an issue for file size.

4. Ungroup arrays after placing them.

This removes the parametric values in the array (uncheck the group & assoc). The constrained parametric values have a tendency to bloat a file.
Keep unnecessary arrays out of families as much as possible.
Common in 3D modeled louvers, but keep them out of families if possible. If doing a detail item and arraying it, consider whether it can utilize the ‘repeating detail component’ tool.
This is counter-BIM ideology, but the program is just not set up to ‘actually’ be great at fully parametric ‘everywhere all the time’… sadly.

5. Keep constraints limited. (Don’t overconstrain).

Keep constraints limited (do not over-constrain)
Do not pin ‘everything’ – keep it to major elements (superstructure)
Do not overlock elements – same as before (superstructure lock to grid)
It’s common to pin and lock things when working on a novice team where people accidentally move items. Consider training and other ways to reduce this rather than this strategy.

6. Limit custom crop regions

Limit Custom Crop Regions = this bloats a file as the crop region is a specific viewport tool. Instead, use a solid white filled region instead and allow the crop region to be a normal rectangle.
“Custom crop regions” are specifically called out by Autodesk as “resource intensive”.

7. Images loaded into the file

Images loaded into a file retain their original size, even if reduced in the view or sheet. (made smaller manually). Therefore, reduce your images in the file prior to linking the images in.
It’s common to place a rendering in your document set. If placing, do not use the full (for example) 5000 x 6000 pixel image. Reduce it down to at most 150dpi (recommend 72dpi) and increase JPG compression in order to get a drastically reduced image with very little clarity loss (In photoshop, Save As JPG with quality at most 6). Images should be kept to <1mb if possible.
As another option, consider providing a Vignette Appendix that lists out your views separately in another package or medium, so you can provide high resolution imagery that way (outside your normal documentation set).
Note: Images also do not get purged from the file through the purge command.

8. Inspect families and reduce sizes of each family

Export the entire family library, and then review and reduce the largest file sizes.
Families with lots of extra meta-data or formulas should be removed if possible. (this happens a lot with manufacturer models). Typically its best practice to save as a manufacturer model and remove all the extra junk they placed into it. Also interrogate manufacturer models more as they typically aren’t modeled by even the company itself.
The vast majority of families should be below 1mb, and almost all families below 3mb. Any family that is above 2-3mb in size should have a very good reason for being that size, and should be actively monitored.

9. Design Options – Use sparingly

Design options are quite literally multiple modeled elements in the same locations. Accept these as soon as you can. Keep this list as small as possible. Use archiving and other ways to try and accept design options as soon as realistic in the project process.
Each item that is in a design option means the program needs to work through more cases and process whether its part of the design option set or not when click or moving, etc.

10. Warnings

Warnings should be monitored. However, it should be noted there really isn’t any ‘rule’ in terms of how many warnings are too many. There are many sites out there that say for every 1mb of central model size, limit to 1 warning. So 500mb size = 500 warnings. There is no validity to these claims though and this is some rule someone created that sounds nice. Ignore this rule and anyone who says it.
The reason there is no ‘rule’ is that warnings vary greatly in the amount of damage they can do to a file. Certain warnings, such as ‘duplicate type mark values’ is an incredibly minor issue, and really more of an annoyance. However, something being ‘slightly off-axis’, could be a precursor to a much larger problem and also can ripple through multiple modeled elements. For example, we’d rather have 10,000 duplicate mark value warnings than 1 slightly off axis warning.
The most important part about warnings is just to make sure you monitor the delta (change) between week to week. If you notice a huge jump from one week to the next, go with the team to figure out what was the change that caused it — perhaps a modeling error, new family, etc.

11. Delete unused sheets & views

Typically doesn’t help much, but if left unchecked for the entire project can make a dent.
The main thing to remember is that Revit is a program designed to create a drawing set, and therefore it does very well with more views and more sheets. It is not necessarily about the number of views or sheets, but the items on the views or sheets.

12. Model in place

Use it for one offs. An example would be a lobby desk for a large building, where it’s only located once within the entire model.
Multiple instances of a model in place? Make it a family. No exceptions.

13. Never import CAD

In addition to bringing in more elements to the model, it also brings in a lot more line types as well as materials and other assets which bloat a file.
This should be a golden rule in your office.

14. Groups

Groups are great, but do not overuse them. This can bloat a file. Use them only when you truly need them. Also make sure to plan out how your groups will function and keep them delineated and clean always.

15. View Detail

Limit what is shown in each view to only what you need. Utilize the coarse, medium, and fine to control this a bit further.
Remember, anything revit has to draw, it has to compute. This is processing power that can be used for other things. Therefore the more things it has to draw within a view, the slower the program will operate.