I am not an expert. But I usually measure from the needle to the bottom of the work. And while I make sure it is nice and flat there is an effort not to stretch it in any way.

I read somewhere that the correct method is to remove your knitting from the needles to make sure it is not stretched at all. Thinking about that gives me a headache LOL.

I measure from the bottom of the needle. Pat the knitting flat, do not stretch it. I saw and expert say you should hold it up and measure it, but I think that would too difficult to get an accurate measure and hold the ruler steady.

OK...thanks Dances and Sheilaj. I thought it would be from the bottom of the needle down.

I measure from the bottom of the needle.