Nipple Sizes: What Parents Should Know

Choosing the right bottle nipple is one of the most important parts of helping your baby feed safely and comfortably. Nipple “sizes” usually refer to the flow rate—how fast the liquid comes out—not the actual shape or length of the nipple. Babies’ feeding needs change as they grow, so knowing when and how to adjust nipple size can make a big difference.

Common Nipple Flow Sizes

• Preemie (Slowest flow): Designed for premature or medically fragile babies who need extra control and coordination.

• Newborn/Level 1 (Slow flow): Best for most newborns learning to coordinate sucking, swallowing, and breathing.

• Level 2 (Medium flow): For babies who are a little older (around 3+ months) and show signs they are getting frustrated with slow flow.

• Level 3 (Faster flow): Used for older babies (around 6+ months) who drink more at each feeding.

• Level 4 or Y-Cut (Fastest flow): For thicker liquids like formula with added cereal or specialized nutritional supplements.

Signs You May Need to Change Nipple Size

• Baby is working very hard, sucking strongly but not getting much milk.

• Baby is falling asleep before finishing feeds (flow may be too slow).

• Baby is coughing, choking, or gulping (flow may be too fast).

• Milk is spilling from the sides of the mouth.

• Baby becomes frustrated, pulls away, or refuses the bottle.

Tips for Use

• Always start with the slowest flow your baby can manage safely.

• Watch your baby’s cues, not just their age, to guide when to move up.

• Hold the bottle so the nipple is partially filled with milk to reduce air swallowing.

• If your baby has reflux, swallowing issues, or special feeding needs, ask your feeding specialist or pediatrician for guidance.

• Remember: every baby is unique—some may stay on a slow flow longer, while others move up more quickly.

Takeaway: The “right” nipple size is the one that helps your baby drink comfortably, safely, and with steady weight gain. When in doubt, follow your baby’s lead and check in with your healthcare provider.

Warm Regards,

Esther A. L. Verbovszky, M.A. CCC-SLP Star Center Foundation