Baby Bottle vs Sippy Cup: Why They’re Not The Same And When To Switch

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U.S. Air Force photo by Lt.Col. Inaam Pedalino

When you bring a new baby home from the hospital, priority number one is figuring out how to feed it.

Formula-fed babies will need plenty of bottles handy, and even breastfed babies will need a few available… at least so mom can have a break every now and then!

Shortly before your baby turns 1, she’ll transition to a sippy cup, but why?

You might be wondering — why can’t a baby just keep using a bottle? And can babies just use sippy cups from the start? What’s the difference between a bottle vs sippy cup anyway?

The main difference between a bottle and a sippy cup is the mouthpiece.

A bottle uses a nipple, and a sippy cup uses a spout. Nipples on baby bottles are designed to more closely replicate mom’s nipples for a baby’s comfort. They’re also better at removing air bubbles from the milk or formula inside the bottle, sometimes with the help of a straw-like device inside or another venting system.

A bottle and a sippy cup both serve the same main purpose, to feed your baby or allow it to drink liquids, but it is recommended for a baby under 9-months-old to use a bottle. As she surpasses 9 months, she can start to transition to a sippy cup. 

Let’s take a little bit of a closer look at this comparison.

Baby Bottles Explained

The classic baby bottle has been around for ages, so it’s very likely you know what it is.

However, nowadays there are so many different styles and designs for the bottle itself, as well as a wide array of nipples, that it can get pretty confusing.

A bottle can be made of plastic or glass, and usually will have some sort of measurement markings on the side to ensure you prepare the proper amount for your baby’s feeding. The nipples can be latex or silicone, and come in a variety of shapes and sizes.

It’s important to try out several options with your baby to find the one that works the best.

A big factor to consider when it comes to the nipple is the size. All nipples contain a small hole where the liquid flows from, and the size of this whole determines how much milk comes out at a time.

A size one nipple has the smallest hole and is best for a young baby, while sizes 2 through 4 have larger holes and are better suited for an older baby.

Basically, you want to check that your baby is getting the appropriate amount of milk at a time; not too fast where she appears to be choking, and not too slow where she is struggling to suck. 

Another factor to consider when choosing a bottle for your baby is the shape of the bottle itself.

Many bottles have straight sides — it’s pretty much the standard at this point. They have been around for years and work very well.

There are also bottles that feature a slight bend, which helps cut down on the amount of air your baby swallows, and in turn, can reduce gassiness and fussiness. This is something to keep in mind, basing your choice on your baby’s unique needs.

Look for a bottle that meshes well with your baby’s feeding and sucking habits. When your baby is small, you can opt for 4-ounce size bottles, but as she grows, it makes sense to move to a larger bottle since you will need to feed your baby more milk at one feeding.

(Learn more about the different types of baby bottles here.)

Pros and cons of baby bottles


  • Mimics the breast well: Bottles were designed to feed babies, it’s what they do. The nipple design taps into your baby’s innate urge to suck in order to feed.
  • Regulates milk flow and air bubbles: Bottles these days are meticulously designed so babies get the right amount of milk when they suck, and most do an excellent job at reducing air bubbles for colic and gassiness.
  • Convenient when you are unable to nurse: Bottles are a great way for others to feed your baby when you are breastfeeding. You can pump and freeze your milk so that your partner or a caregiver can use a bottle to feed your baby.


  • Can become a security blanket: Even though bottles are necessary, they can also become habit-forming if you don’t wean your baby off of them at an appropriate time. Your baby will start to start to treat her bottle as a pacifier, instead of just a way for her to get food.
  • Can potentially lead to dental and speech development issues: If your baby stays on a bottle for too long, it can start to interfere with the positioning of her mouth, teeth, and tongue, which could in turn cause issues with speech development. Also, if you let your baby have a bottle of milk or juice at night in her crib, this can contribute to cavities and tooth decay.

When my daughter was young, we found Dr Brown’s bottles to be the best. You can check them out on Amazon here.

Sippy Cups Explained

A sippy cup is the usual natural progression for a baby after the bottle.

In fact, many bottles are designed with interchangeable tops, so you can use a sippy cup spout in place of the nipple.

Using a sippy cup helps your baby bridge the gap between a bottle and a regular open cup, or at least a cup and straw.

You can start to introduce your baby to the concept of a sippy cup when she is still relatively young, about 6-months-old, even though she will still be drinking from her bottle. 

Once a baby is between 9 and 12 months of age, this is a good time to start to wean her off of the bottle.

The goal should be to completely transition to the sippy cup by one-year-old, or at the latest, 18 months.

Sippy cups allow babies and toddlers to drink without spilling, like bottles, but aren’t as concerned with milk flow and air bubbles.

Sippy cups come in all sorts of sizes, styles, designs, and colors. They also come with several different shaped spouts, and some are even designed to more closely resemble regular cups.

There are sippy cups with handles and those without, but all of them, of course, have a lid.

Since sippy cups come with a lid, it can be very tempting to let your child carry it around everywhere she goes since she can’t spill her drink, but this can become a big habit that is hard to break.

Pros and cons of sippy cups


  • No spills: Since all sippy cups come with lids, you don’t have to worry about spills as your baby gets the hang of drinking from her cup.
  • Good transition: Sippy cups provide a good transition from a bottle to a regular cup, giving your child more control over when and how she drinks.
  • Versatile: Sippy cups come in an almost endless array of colors, sizes, and designs, so you are sure to find one that your baby will be happy to use.


  • Can be habit-forming: Just like a bottle, if your child is not weaned off of a sippy cup properly, it can soon become her security blanket.
  • Can cause issues with speech and dental development: Sippy cups aren’t immune from causing dental or speech problems if used improperly or overused. Dentists recommend diluting juice and limiting ow often you let your child drink from a sippy cup.

My daughter was obsessed with these Munchkin trainer cups when she was little. They simulate sipping from a regular cup and encourage great motor control. See them on Amazon here.

Wrapping Up

That about sums it up when it comes to the differences between a baby bottle and a sippy cup.

It all comes down to the mouthpiece. Bottles use a nipple that resembles a human nipple — it regulates the flow of liquid perfectly and removes as many air bubbles as possible.

Sippy cups are more like drinking from a regular cup (or a cup and straw) that can’t spill, and they’re more for teaching children the coordination and motor skills to eventually use standard cups.

Stick with the expert recommendations here. Use a proper baby bottle for newborns and begin transitioning to a sippy cup close to the 9-month mark.

Hope this helps!

And before you go, check out more baby stuff explained like: