Here is a nipple piercing for which I only pierce with a 1.6mm needle. The length of the bar, like with most piercings but especially for the nipple; will be longer than needed to accommodate initial swelling. The nipple can be one of the longer healing parts of the body to pierce, although I have to say men tend to heal a lot quicker (roughly within 3-6 months) whilst women can take longer (6-12 months) due to the area being more sensitive and obviously functioning differently. Nipples do require a lot of attention regarding aftercare, but a shorter bar or a ring can be fitted when it’s fully healed.