How wide are the units? How wide are the frame members? A picture of the elevations would be helpful........

Is this an upper cabinet or a base cabinet? Are they framed with a style in the center or frameless cabinets? Thomas is right we would need more info to go on.

They are upper cabinets, yes they are framed with a style in the center. The units are 3.5 feet each apparently. Let's put it this way, I have 14 ft. of space and she's got eight cabinets, or four units.

If you had 14 feet of cabinet space on the cad drawing, how many cabinets would you put?

To answer your original question – there is no “normal”. We would ask “What’s going into the cabinets” and plan accordingly.

Wall cabinet openings less than 12” are useless and openings of greater than 24” are not typical. 21” is large but not out of the norm.

I don’t want to through your designer under the bus, because sometimes budget plays a role in the design. Less cabinet boxes and fewer doors equal less money.

Ah! ........ Ok, thank you!

And if you have a cabinet maker build them for you, you can dictate exactly what you want, height, width and depth as well as style and color - you wont be restricted to 'standard' sizes and pre-made catalogued pieces. It actually costs less than going to a discount DIY home center and they will usually work on finessing your design with you as they have to draw it to cut their pieces .....

One of my base cabinets is 1'-6" wide and family members keep running into it while trying to access inside, and now the hinge just broke off.

Yes! My cabinets are to be custom built. It just seemed to me they were a little wide. But if you put 5 units in there instead of 4, then they look too skinny.

If you consider the space left for the ends and in between each unit, then they are a little more narrow.