It can vary and Tsuga canadensis can be quite wispy up top. Given the DBH of a 7 or 8 footer is nearly halfway up the tree it may only be 2 or 3 inches.

tj

Ah, how to measure a tree. Who's got their anla manual?

You have two competing schools here, forestry and horticulture. Horticulture lease diameter at six inches above soil line up to I think four inch caliber, then at 12 inches above until 6 or 8 inch caliber, then duh.

Forestry largely deals with larger trees, and deals in dbh.

I used to live in a municipality where the city inspector sanded bark ridges down and used mechanics calipers.

And most people only care how tall the thing is...which is not how stick is graded, unless you're talking really small stuff, and even then, caliper is the official grading standard, even if most nurseries list by height.

Evergreens are to be graded by height, unless sheared, in which case, caliper is the official (if mostly disregarded) measurement criteria.

Otherwise, you just got to get in their and measure. If they have decided this is how they measure, so be it.

So I'm going with the answer not provided, that more information needs to be given to understand what's going on. I assume there is some kind of covenant, escrow with holding, or landscaping code/ordinance that requires a plant of a certain size. But usually, in the case of evergreens such as hemlock, the guidelines specify a height...at least what I've run across.

I did an internet search and learned the difference between DBH and caliper. I was not aware that there was one! According to this blog, I learned that the city's use of the term "caliper" means that I can measure the tree at 12" from the ground and not DBH. Before I didn't know there was a difference! So in the future I guess I need to measure trees at 12" instead. I guess that would change my original question, tsugajunkie z5 SE WI ♱. It now appears that I am looking for the caliper measurement of a 7-8ft Canadian hemlock, and not DBH. What would be your estimate of that?

Here's a picture of a small Tsuga Canadensis I took while visiting the Hemlock Ravine SNA last year. It was about 8' tall if I recall correctly, possibly a foot or so more. What would you say it's diameter is at 12" otg? 1-1/2"? Possibly 2"?

The little dead Hemlock to the right was a little over 2 ft. tall.