Well - first the question is - are we talking about your overall head, or your individual strands.
You can have fine/medium/coarse strands of hair - that's talking about the actual size of each hair strand.....
Fine - Thin strands that sometimes are almost translucent when held up to the light. Shed strands can be hard to see even against a contrasting background. You can also try rolling a strand between your thumb and index finger. Fine hair is difficult to feel or it feels like an ultra-fine strand of silk
Medium - Strands are neither fine nor coarse. You can also try rolling a strand between your thumb and index finger. Medium hair feels like a cotton thread. You can feel it, but it isn't stiff or rough. It is neither fine or coarse.
Coarse - Thick strands that where shed strands usually are easily identified against most backgrounds. You can also try rolling a strand between your thumb and index finger. Coarse hair feels hard and wiry. As you roll it back and forth, you may actually hear it.
And, you can have thin/average/thick density of hair - that's talking about the density and the number of hairs you actually have on your head....
The 'classic' method of determining your hair density is the simplest of the measurements, as all it requires is hair long enough to put in a ponytail, and a measuring tape. You simply have to measure the circumference of the ponytail. If you have bangs and/or you can't get all of your hair in there adjust according to how much of your hair you have measured.
To measure the circumference - take a piece of string, or a soft tape measure (the kind used by dressmakers). Wrap the string or tape measure around your ponytail - just below the elastic you have in to hold the ponytail together. Read the corresponding number from the tape measure, or hold the string at the length you've measured and use a ruler to determine how much it is. The number given is the circumference of your ponytail.
i - thin (less than 2 inches/5 centimeters)
ii - normal (between 2-4 inches or 5-10 centimeters)
iii - thick (more than 4 inches/10 centimeters)
So. Usually the coarser your hair, the thicker it is - but not always.
You can have fine thick hair. You can have coarse thin hair. You can have fine average hair - and so forth, and so on.
Hope that helped, some...
