What is the optimal size for the head texture ?

for example 500x500 because you can make it on paint.

and sometimes its to big.

Optimal sizes to draw on would be a 500x500 Head Texture, which I suggest that you do it in Photoshop or GIMP.

You'll need the 500x500 head-texture item to actually be able to USE the head texture at it's best resolution, or else it'll get scaled down and the quality will be significantly decreased (I think... >.>)

First of all, it's a 512x512 texture.
It depends on what head texture item you're applying the head texture to.
If you have a 128x128 head texture, apply a 128x128 texture.
If you have a 256x256 head texture, apply a 256x256 texture.
If you have a 512x512 head texture, apply a 512x512 texture.
Simple.
You could always mix 'n match the textures with the texture items, but it will appear in very (excuse my language, but it's true) shitty quality.
I.E. Putting a 512x512 texture to a 128x128 head texture will appear to be in very bad quality.

i buy just the head texture for 2000 tc their dont stand the size...

textures-body textures-head texture if you scroll down...

so what size,,,

For 2000TC, you probably purchased the 128x128 head texture item. You need to either make your head texture image in 128x128, or make it in 512x512 and scale it down.

okey ty

A head texture image is not a spinning image you see floating around in the market. Thats a preview, thats how the head will look in 3d when you really wear it.

The original head texture image is a flat one. When you upload it, it automatically merges with the both sides of the layers. Texture makers have to make it special for not a line to appear once you wear it ingame, at the back of your head, Here's a list of some good texture makers if you are interested to order one.

-fireeyes
-kamura
-Leaph
-gabiel

If you want a custom head texture, PM them with you choice, and they may tell you to offer the price or they may tell it themselves.