When to Switch Baby Bottle Nipple Sizes: Knowing The Right Time & Right Way

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A baby is drinking milk in her mother's arms

Does your baby seem to be getting frustrated with the bottle? If so, you might wonder whether it’s time to switch your baby’s bottle nipple sizes. If it is time to change nipple sizes, then you wonder how to do it.

Picking the right bottle nipple sizes makes feedings more comfortable enjoyable for everyone involved. However, you might wonder how do you know what the right size nipple for your baby is and when to move up a size.

Let’s take a look at all of the questions you might have about nipple sizes and switching sizes.

Feeding your baby is an important task, but it should also be an enjoyable time for both you and your baby. However, baby bottle nipples wear out over time, and your infant’s need will change. He will be able to eat faster, and a smaller nipple prohibits eating at the pace he desires.

You might notice that your baby becomes frustrated during their feedings, and it leads to a stressful situation. Nipples that are too slow make your baby work harder to get their milk, leaving your baby feeling irritated and crying more often.

The Different Baby Bottle Nipple Sizes

There is a variety of baby bottle brands and bottle nipple sizes. For each type of bottle, you’ll find different nipples, and that can be confusing. Unfortunately, no standard system that works for all bottle brands exists, so you do have to refer to your specific brand for age recommendations.

However, here are the general ages you’ll see for these sizes:

  • Preemie Nipples: Preemie nipples are meant for babies 0+ months.
  • Level 1 Nipples: Level 1 nipples are for babies 0+ months.
  • Level 2 Nipples: Level 2 nipples are for babies 3+ months.
  • Level 3 Nipples: Level 3 nipples are designed for babies 6+ months.
  • Level 4 Nipples: Level 4 nipples are meant for babies 9+ months.
  • Y-Cut Nipples: Y-Cut nipples are for babies 9+ months.

Remember that you should follow your specific bottle brand and the corresponding age for each level. There are some general rules you can follow to get started if you’re unsure about what level.

1 Babies under three months old should use a slow or newborn nipple, which might be labeled preemie nipples or level one.

2 Between the ages of three and six months, babies can use medium flows, which are typically level two and three.
3 Once your baby is nine months old, he can use the fastest flows.

The Different Types of Bottle Nipples

Bottle nipples come in many styles. Let’s take a look at the shapes and other varieties to help you make the best choice for your baby.

1. Bottle Nipple Shapes

Standard nipples are the tall, dome-shaped that are designed to mimic the shape of a mother’s breast. Most babies prefer the standard nipples, and every brand sells these types of nipples.

Orthodontic nipples are shaped to fit inside of your baby’s mouth. They’re full at the tip and base while being narrow in the middle. Most have one flat shaped on the nipple.

2. Bottle Nipple Materials

Nipples come in two general materials: Latex and Silicone


  • Softer
  • Holds the Odor of Milk
  • Wears Out Faster


  • Sturdier
  • Easier to Clean
  • Lasts Up to a Year

When To Switch Bottle Nipple Sizes?

The bottle nipple sizes that you use for your baby will depend on if they’re formula fed or breastfed, along with their age and readiness cues.

1. Formula Fed Babies

To best determine the nipple size for formula fed babies, check out the age and flow that your bottle brand recommends. Each brand should offer a guide that shows the suggested ages to switch nipple sizes. Of course, the most important factor is to follow your baby’s individual cues and attitude while eating.

Formula fed babies should start off with the slowest flow nipple at birth. The slowest flow is meant for younger babies who don’t eat as much in a single setting, and their swallowing isn’t coordinated enough for faster flows.

Age is a factor that, but it’s not the most important factor when it comes to switching nipple sizes. If you watch your baby close enough, you’ll notice that babies give signs that they’re ready to move up sizes. Some of these signs include:

  • Sucking harder on the nipple
  • Collapsing the nipple
  • Becoming visibly frustrated
  • Pushes the bottle away
  • Smacks the bottle
  • Takes 30 minutes to an hour for a single feeding
  • Still hungry soon after feeding

Babies who aren’t displaying these signs typically are okay with the nipple size that they’re currently on. If you aren’t sure, you can move up a nipple size. It doesn’t have to be a permanent change!

2. Breastfed Babies

Breastfed babies drink at a different rate that bottle fed babies. You want to pick a nipple that closely resembles what it is like to breastfeed. Breastfed babies are used to having to work a bit harder for their milk because the breast releases milk at a much slower rate.

Breastfed babies who are taking a bottle should start with the slowest flow nipple that your bottle brand offers. Most breastfed babies never need to move up a nipple size because breastmilk is thinner than formula. It flows through the nipple much faster than formula.

Moving a breastfed baby up to a faster nipple flow can cause your baby to become impatient at the breast. Some babies start to refuse the breast when they get used to a fast flow of the bottle, so breastfeeding mothers need to be careful.

If you do think you might have to move up nipple sizes, watch to see if your bay only takes five to ten minutes at your breast but gets frustrated with a bottle. If he takes a considerably long time to finish them, it might be time to move up.

What Size Nipple to Use if You’re Exclusively Pumping

Exclusively pumping parents find themselves a bit in the middle. Their baby is breastfed but only uses bottles. If you’re exclusively pumping, you’ll often find that the same rules apply as if you’re breastfeeding.

It’s easy to overfeed babies with bottles, so use the slowest starting nipple. Babies digest breastmilk much faster than they are able to digest formula because it’s thinner. Parents must establish proper habits when bottle feeding with breastmilk. Babies should still feed on demand, but try using paced feeding techniques and stick to slower flow nipples to mimic natural breastfeeding.

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How to Switch Baby Bottle Nipple Sizes?

Switching the nipple sizes is relatively straightforward. First, unscrew the top of the bottle away from the container. Remove the nipple from the ring and put the new nipple into the ring. Then, screw the top back onto the bottle. You’re done!

Depending on the brand that you use, you might have some extra attachments, but each manufacturer should provide directions to switch nipple sizes and assemble correctly.

The Dangers of Changing The Nipple Size

Using a flow that is too fast for your baby can cause him to suffer from some serious side effects. A faster flow poses a choking hazard and can cause negative impacts on digestion. Moving up to a flow that is too fast causes your baby to struggle with the flow of milk, and she might swallow too much air. That leads to painful gas and gut issues later.

Signs to Watch to Make Sure the Nipple Size is Correct

If you aren’t sure if you made the right choice for nipple sizes, watch for signs that your baby is struggling, such as:

  • Choking
  • Gagging
  • Milk dripples out of his cheeks
  • Uncomfortable after eating

These are signs that the flow is too fast, so change it back to the size you had previously until your baby is a little bit older.

Wrapping It Up

Using the right baby bottle nipples sizes make feedings go more smoothly, making it an enjoyable time for you and your baby. Remember what works for one baby doesn’t necessarily work for the next baby. Your first child might be content staying at the same nipple size for months, and your next baby might switch sizes more often. It’s not a one size fits all thing.

Don’t feel the need to change bottle nipple sizes until your baby is showing signs that he’s frustrated with the current size. Pay attention to your baby’s attitude and behavior to decide if it’s the right decision. If your baby shows that moving nipple sizes was the wrong idea, switch back to the previous size.

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