Terminal length of vellus hair

Hello, i would like to ask how long can vellus hair grow? I have noticed recently some 4mm to 1 cm hairs on my back, hips, simply everywhere. It just made me wonder. They are slightly pigmented, but they are much smaller and finer than hair on my chest or stomach or arms. Any idea if those are vellus or terminal hairs? any way to find out by myself? Thanks.