This is just my opinion, but I always think "pussy posing as a tough guy" when I see upside down cross tattoos. I know a guy who has one on his neck. He's a pussy. Just saying.
I'll answer anyway. Most forearm tattoos run top to bottom, the same as your arm. Therefore, the long part of the cross should be closer to your forearm and the short part closer to your hand. This goes for any tattoos on the arm, so do not take my advice as suggesting you should actually get this tattoo.
I'll answer anyway. Most forearm tattoos run top to bottom, the same as your arm. Therefore, the long part of the cross should be closer to your forearm and the short part closer to your hand. This goes for any tattoos on the arm, so do not take my advice as suggesting you should actually get this tattoo.