Bigger the better.

More importantly - dual monitors. The actual size doesn't matter too much to me, but having two side-by-side displays is *crucial* for desktop work.

I would imagine there's a bit of an efficiency curve for size though? If you sat at a 3ft wide desk, I'd imagine a 65" monitor would not be an effective use of space nor very ergonomic.

Would be great to know your actual size(s) being used to get a more specific understanding of the average.

Thanks!

I need more flat desk space for drawings and notes than vertical monitor surface.  Two 22"ish monitors set about 2' away from me is as much as I need.  The 2nd monitor serves only as an Archinect portal.  

As others have said.  Size is secondary to quantity.  Two monitors is an absolute necessity. 

Thanks for the responses so far - let's assume we already use dual monitors and will continue to do so.

Size is tertiary to resolution which is secondary to quantity. Nothing worse than having two monitors at a terrible resolution.

Min. 2, 20"-24" probably

Dual screens plus an iPad, laptop for portability,  and the phone screen. All as big as I can get them. Or per desk size.

Size is quaternary to ergonomic set up of monitors, which is tertiary to resolution, which is secondary to quantity.

I use a 15" laptop with 24" second monitor (1080p resolution) when at a desk.

Laptop screen gets email / web / etc. while second monitor is where the actual "work" happens (Revit, AutoCAD, photoshop, etc.)

In this setup it works best if your external monitor resolution is the same as whatever the native resolution is for your laptop.  In my case I have to "dumb down" the resolution of my laptop (native 4k) to 1080p in order to avoid weird scaling issues.

Minimum 2 24'' 1080p monitors. I have 27'' myself. Any bigger is difficult. 4k monitors if you doing lots of graphics work or renders.

Size is quinary to ergonomic set up of monitors, which is quaternary to identical monitors, which is tertiary to resolution, which is secondary to quantity.

Whatever's available to me, at my previous job I set up 2 monitors hooked up to a windows machine, a macbook pro on the side table next to my smartphone. Wasn't more productive, more distracted to be honest. All this presumed multi-tasking is not for me I found out, always had archinect open somewhere. Whatever you prefer, as long as you have this as your wallpaper on at least one of the screens to mess with your supervisors you'll be okay:

A pair of 27" on an adjustable monitor arm.

Monitors? How quaint.

VR? Obsolete.

3D holographic projection is where it's at.

At my office of about 50 designers everyone has 2x27 inch screens. 

Typically I will have email on one and revit on the other. 

Although I’m not a huge fan of revit, I use it extensively and I really love how 2019 has introduced tabs that are like a browser. So now I tend to have a 3D view full screen on one monitor, and the plans/sections etc on the second monitor.