What is the average nock height for folks that shoot 3 under.

You're going to get answers all over the map.  You might be able to narrow it further if you specified whether they're shooting 3U on a bow tillered for it or or split.  But IMHO, after reading a bunch of these inquiries, the consensus is going to average about 5/8ths inch above square w/ arrow nocked under (and double nock sets).

Thank you sir, it is tillered for split.

5/8" is about average for me, although there are a few bows I have that were tillered for 3 under that could go 1/2" or even 3/8".  Frankly, I'm inclined to set them all on 5/8", since that seems to give me a more consistent POI among different bows.

I have found that as my form and release improves, my nock point has gone down.  A few years ago I would have said my average was 3/4."

I have found good luck with 1/2" from center to bottom of nock, be it tie on or brass.  Each of my Widows seem to like this, as does my Yellowstone Half-Breed.  Due to the adjustabillity of my Hoyt Excellafo I could use a figure other than 1/2", but I set it there and am happy.

5/8 on most of my bows.>>>-----> Ken

I tiller my bows for 3 under and set the nock at 3/8th.

Just moved mine up from9/16 to almost 3/4.  I shoot 3 under.  This move solved my tuning issues as shaft had been boucing off the shelf.
Now im measuring to the bottom of the top nocking point.  How are you guys measuring?

3/4 for me

Got mine sorted today. Border black Douglas hex 6 BB2 tillered for split finger, shooting 3 under. Nocking point is 1/2" shooting BE Rampage shafts.