Steve and Alex are Minecraft’s two default player body shapes. They are identical in every way except one: arm width. Steve arms are 4 pixels wide. Alex arms are 3 pixels wide. That single pixel difference means the arm regions sit in different places on the 64×64 skin texture sheet, and the converter needs to know which layout your skin uses in order to read the arm pixels from the right location.
Every other body region — the torso, the legs, the head — is the same size and in the same position for both models. Only the arms differ.
Steve is the original Minecraft body model, present since the early versions of the game. The arm region on a Steve skin is a 4-pixel wide column of texture, giving the character that recognisable chunky, square-armed look. Steve was the only body type until Minecraft 1.8 (released September 2014), so any skin made before that update is automatically Steve.
On the texture sheet, each Steve arm face is 4 pixels wide and 12 pixels tall for the upper arm, and another 4×12 block for the lower arm. The arm sleeve overlay (for things like rolled-up sleeves or gauntlets) sits directly below in a matching 4-pixel wide region.
Alex was introduced alongside Steve in Minecraft 1.8 as an alternative default skin. The only structural change from Steve is that the arms are 3 pixels wide instead of 4 — giving the character a slightly slimmer profile. This model is sometimes called the “slim” model for that reason.
On the texture sheet, the arm face for Alex is 3 pixels wide, with an empty (usually transparent or black) fourth column where Steve’s texture would be. If you look at an Alex skin in an image editor and see a visibly thin gap or empty column on the right edge of the arm region, that is the tell.
There are a few reliable ways to check:
Open your skin PNG in any image editor that shows pixel coordinates (Windows Paint, GIMP, Photoshop, or a web editor like Piskel all work). Navigate to the area starting at approximately x = 44, y = 16. This is the top-left corner of the right arm on the texture sheet. Count how many pixels wide the painted arm face is. Four pixels wide means Steve; three pixels wide (with an empty or transparent fourth column) means Alex.
If you downloaded the skin from a skin site like NameMC or The Skindex, the listing almost always labels the model type. Look for “Steve”, “Alex”, “Classic”, or “Slim” in the skin details. Classic and Steve refer to the same 4-pixel arm model; Slim and Alex refer to the same 3-pixel arm model.
If the skin is on your own Minecraft account, log in at minecraft.net and go to your profile skin settings. The skin editor will show you which model the skin is assigned to. Note that you can assign any skin to either model in the account settings, so the assigned model and the actual skin art may not match if someone changed it after creating the skin.
The converter reads the arm texture pixels from different positions on the skin file depending on which model you select.
If you pick Steve for an Alex skin: the converter reads 4 pixel columns of arm data, but the fourth column in an Alex skin file is empty or transparent. The resulting Roblox shirt arm will have a column of blank or garbage pixels on one edge, leaving a visible gap in the arm texture.
If you pick Alex for a Steve skin: the converter reads only 3 of the 4 painted arm columns, cropping the rightmost column. The arm texture on the Roblox shirt will be missing one pixel column and look slightly squashed on one side.
Neither error is catastrophic — it is one pixel — but it is noticeable when you look at the arms closely in Roblox Studio. The fix is simple: go back to the converter, select the correct model, and re-download the templates.
Skins in the old pre-1.8 format are 64×32 pixels instead of 64×64. If you upload a 64×32 file, it is always a Steve skin — the Alex model did not exist when 64×32 was the standard, so there is no such thing as a 64×32 Alex skin. The converter detects the legacy format automatically and treats it as Steve without you having to do anything. A fun fact about the old models of skins was that you actually only had one arm and one leg texture, it was replicated on either side, which is pretty interesting when you consider that when you think of minecraft skins in the top 10 you think of one of them is most definately the boy in a hoodie holding orange fire in one hand and blue in his other.
If you genuinely cannot tell which model your skin uses, convert it twice — once as Steve and once as Alex — and compare the arm region of the two shirt templates. The correct one will have a clean, solid arm face. The incorrect one will have a visible gap or a cropped edge on the arm.
Open the converter and upload your skin to get started.