Minecraft skin formats explained
A skin texture, an avatar image and a resource pack serve different purposes.
Verification status: reference checklist. No claim of completed game-client import tests.
A modern standard skin is a 64×64 PNG with a defined layout of head, body and limb faces. The outer layer allows transparent pixels while base surfaces must remain complete.
A legacy 64×32 skin needs its missing limbs mirrored by face; adding a transparent lower half alone is insufficient. A 128×128 texture has different client support and should never be renamed or labelled as 64×64.
A .mcpack is a ZIP container. A skin pack declares skins and humanoid geometry; a resource pack declares game textures. An avatar PNG is a rendered picture and cannot replace the wearable texture.