How Long Do Babies Use 2, 4, 5, 6, 8-Ounce Bottles? [Brands Guide Incl.]

Balint Horvath, PhD

Writer, parent, and veteran of baby feeding battles.


How long babies use 2, 4, 5, 6, and 8-ounce bottles is dependent on a number of factors. From age to growth spurts and how hungry they’re feeling on any day or time, your baby can transition from one bottle size to another accordingly. How long babies use 4-ounce bottles could be very different from when they’re using other sizes as they grow and develop. 

A newborn uses a 2-ounce bottle for one month before moving to the next size for another 4 weeks. Older babies use 5 to 6-ounce bottles for 8 weeks before converting to an 8-ounce bottle from five to six months old. Bottle size is dependent on the baby’s growth and development. 

Key takeaways

  • Your baby’s growth and development stage will determine how long they use different-sized bottles.
  • Newborns use 2-ounce bottles for the first 4 weeks 
  • 8-ounce baby bottles are designed for babies that are 6 months old 
  • Choosing the right-sized bottles prevents over feeding

How long do babies use different-sized bottles?

How long babies use different-sized bottles is mainly dependent on their growth and development stages. Feeding times make a difference too with babies being hungrier in the morning, afternoon., or evening. Having different-sized bottles does help to manage your baby’s growth spurts and varying appetite!

A general feeding guide will help you understand how much infant formula or breastmilk babies need at various milestones. Knowing how much a newborn drinks compared to an older baby helps you to get the right-sized bottles for the different stages of growth. 

2 oz bottles

The length of time a baby uses a 2 oz bottle is normally around 4 weeks. Newborns have tiny tums that are still developing and they can only consume 1 to 2 ounces of milk at each feed. 

A 2-ounce bottle holds just the right amount of breast milk or infant formula. If you opt to use a 4-ounce bottle for your newborn, make sure you only fill it to the 1 or 2-oz mark to prevent overfeeding. 

4 oz bottles

When your newborn reaches four weeks old, they’ll use the 4 oz bottle for another 4 weeks, until they reach two months old.  At one month, your baby is drinking between 2 to 3 ounces of milk, 8 to 12 times per day. 

To meet your one-month-old baby’s nutritional needs, it’s important to match the bottle size with the recommended quantity of formula or breast milk required for healthy growth and development. 

5 oz bottles

Your two-month-old baby will use the 5-ounce bottle for up to eight weeks until they reach four months. When your baby reaches eight weeks old, you can switch over to the 5 oz bottle. At this stage, some parents even skip to the 6-ounce bottle. 

Skipping straight to 6 oz bottles saves money and lets you use this size for longer as your baby gets older.

6 oz bottles

Four to six-month-old babies will use 6 oz bottles for eight weeks. If you’re using this size bottle from when your baby is two months old, they’ll use it for sixteen weeks. When using 6 oz bottles for eight to sixteen weeks-old babies, make sure you fill the bottle to the right measurement so you don’t overfeed your little one. 

8 oz bottles

Babies from six months old and older will use 8 oz bottles for 6 to 12 months. A six-month-old baby consumes between 6 to 8 ounces of milk per feed. It’s recommended to wean your baby off bottles by the time they reach 18 months old. 

When does a baby start using sippy cups? 

Babies can start using sippy cups between 4 to 6 months of age when they are able to sit up and hold objects with their hands. Sippy cups are a great transition from the bottle to a regular cup, as they have a spout or straw that allows babies to sip liquids without spilling. 

It’s important to choose a sippy cup that is appropriate for the baby’s age and developmental stage, as some cups have different spout shapes and flow rates. Parents should also supervise their baby when using a sippy cup and encourage them to drink water or milk instead of sugary drinks.

When should I switch to 8 oz bottles?

The best time to switch your baby to 8 oz bottles is when they reach six months old. By the time your little one reaches this stage, they’re consuming anything between seven to eight ounces of infant formula per feed. Your six-month-old baby will be feeding six to eight times daily so make sure you have enough bottles to get through each day. 

How many baby bottles are needed for every age

The number of baby bottles you need for every age is dependent on the following factors:

  • The number of feeding times during a 24-hour period
  • How often you’re cleaning the bottles
  • The size of the bottle
  • If your baby is going to daycare
  • How many bottles do you need to prepare in advance
  • If you have twins or triplets
  • Your budget

If you’re cleaning bottles after every feed, you won’t need as many bottles. However, the more feeding times your baby needs, the more bottles you’ll need if you’re only washing once or twice a day. If your baby is going to daycare, you’ll need to pack an extra bottle for emergencies, and having spare bottles are useful if you like to prepare them in advance.

Using the right-sized bottle for the age and growth of your baby means you only need one per feed. The number of bottles doubles or triples if you have twins or triplets! And, finally, your budget will determine how many bottles you can purchase when bottle-feeding your baby. 

The general rule of thumb is to have eight 2-ounce bottles for your newborn. If you’re supplementing with breastmilk, you can bring the number of bottles down to three to four bottles. When your baby reaches two months old and older, you can have four to five bottles. But, remember to have some spares for daycare stays, traveling, and preparation in advance.

Knowing how many baby bottles and nipples you need is dependent on the various factors I’ve mentioned so far. Other factors to consider include the following:

  • Exclusively pumping with no infant formula
  • Expressing and freezing breastmilk
  • Packing spares for the diaper bag
  • Using disposable baby bottle liners

Why is it important to choose the right bottle size for your baby?

The importance of choosing the right bottle size for your baby is strongly emphasized to prevent overfeeding or underfeeding from happening. Here are some facts about why choosing the right-sized baby bottle for your little one is essential:

  • Nutritional deficiencies: Underfeeding your baby can result in nutritional deficiencies which will hamper your little one’s growth and development. Using the right bottle size minimizes the risk of giving your baby too little infant formula for their age. 
  • Underweight: Underfeeding your baby can result in them becoming underweight because of a lack of nourishment. Having the right-sized bottle helps prevent this from happening as you’ll be able to give them the exact volume recommended for your baby’s age. 
  • Overweight: Overfeeding your baby can result in abnormal weight gain leading to obesity and other health issues. Using the correct bottle size at each age prevents you from giving your little one more than they need at each feed especially if they’re guzzlers!
  • Vomiting, gas, and spitting up: Giving your baby too much infant formula during a feed can cause them to suffer from uncomfortable gas, bloating, vomiting, and spitting up. These unpleasant conditions can be reduced by keeping to the right quantity of food at each mealtime. 

If your baby remains unhappy after each feed or you notice any of the above conditions surfacing, speak to your medical doctor or pediatrician. They can advise if you need to increase or decrease feeding quantities and check for any other potential health problems. 

Watch this video to find out the side effects of nutritional deficiencies in babies.

Brands that offer various-sized baby bottles 

Use this table to give a quick overview of popular baby bottle brands and the sizes available. 

BrandBottle Sizes
Comotomo5oz and 8oz
Dr. BrownStandard bottles: 2oz, 4oz, and 8ozWide-necked bottles: 5oz, 8oz, and 9oz
Evenflo5oz, 8oz, and 9oz
MAM90ml, 130ml, 160ml, 170ml, 260ml, and 270ml
NUK150ml, 260ml, and 300ml
Philip AVENT2oz, 4oz, and 9oz
Tommee Tippee150ml, 260ml, and 340ml

Please note that some brands produce a range of models that may only come in two or three different sizes. For instance, anti-colic or glass bottles may only be available in 4 oz and 8 oz sizes. If you decide to purchase bigger bottles for your younger baby, make sure the measurements are easy to read and that they include smaller volumes. 

If you want to compare some popular sizes for baby bottles, you may want to go into the details on 4 oz and 8 oz bottles or 9 vs 11 oz bottles which I wrote about in separate articles.

A quick tip! Picking bottles that are dishwasher-safe saves you a lot of time at the kitchen sink, hand washing after each feed. 


Getting the right bottle size makes a world of difference when you want to ensure your little one gets what they need at any stage of their growth and development. The right-sized baby bottle prevents overfeeding or underfeeding as well as waste from leftovers! Knowing when to transition your baby to the next size helps you to plan when to purchase bigger bottles.

Whatever your favorite brand is, when comparing wide-neck vs narrow bottles remember that standard and larger designs do come in different sizes. If you can’t find 2-ounce bottles for your newborn, don’t stress! Many parents use the 4 oz bottle successfully, using the 2 oz measurement. Just double-check this measurement is available!

Photo of author


I’m Balint, founder of this site and a father (and dad) to a baby-turned toddler. I found the world of babies so fascinating that I started a blog dedicated only to that topic. By the way, I studied physics, engineering (PhD, MSc), and therefore I do a thorough research when I write about something. Since it’s a blog, of course I also write about my personal experiences.

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