Look at the size of the pink compared to the snake. If the pink is one to one and a half times the diameter as the widest part of the snake, then it is the right size. If the pink is way smaller, then feed two. If the snake is new, it's ok to start out conservatively for a couple meals. I think it's difficult to weigh items of 1-5 grams- unless you have a very fine scale. I mean, mine reads in one gram increments, but I don't think it accurately weighs 1-2 gram pinks. I visually sort them from smallest to largest into about three groups, and start feeding from the smallest up.