How to measure arms with alot of fat?

Ok, this sounds easy, but it's not.

I have the myotape tape measure because it's easier to use than a regular one.

it works like this:  http://www.bodybuilding.com/store/acc/myotape .html

The only problem is, I can't seem to get an accurate measurement of my arms because the fat on/under them is too soft, and it just hangs there. So the tape kinda cuts into the fat, and shrinks to fit the muscle underneath.

But what I want is to measure how big my arms are, including an accurate measurement of how much fat is on them. Because my arms are untoned, I can't seem to get a accurate measurement of them. If they had less fat and more muscle, I probably could.

I tried to measure how much hanging fat there was, and I think the closest estimate was about an 1 1/2", possibly 2 1/2".

 With the myotape around the circumference of the fullest part of my arm (around the middle), the closest measurement I could get was 15 1/2", but I don't know if that's correct. I've been on cc for about a month and a half, I do alot of arm workouts, free weights, the gym lat pulldown machines, and I don't see any real change. I think it's because I need to lose overall body fat and then the fat on my arms will decrease, right?

Measuring any other not-as flabby part of my body is easier, though.

The idea of measuring body fat is to find out your overall bodyfat percentage. 

The idea isn't to measure the fat on your arms, then thighs or anywhere else.  You cannot spot reduce any part of your body.  To reduce the amount of fat on your arms and improve muscle definition, you need to reduce your overall body fat through diet, weight lifting and High Intensity Interval Training.

Diet is the most important.  Your weight lifting routine should include compound lifts (multi joint) such as Deadlifts, Squats, Bench Press, Overhead Press, Chin Ups and Dips. Don't worry about isolation exercises such as bicep curls or tricep kick backs.

I don't know much about this Myo Tape thing, but I'd suggest that fat callipers are better.