9 oz vs 11 oz Bottles – Which One to Use

Balint Horvath, PhD

Writer, parent, and veteran of baby feeding battles.


Baby bottles range from 2 oz to 11 oz in size which could get you wondering which is best for your little one’s bottle-feeding needs as they get older. When comparing 9 oz vs 11 oz bottles there are some differences to take into consideration before deciding which is better for your baby. 

Babies can switch to 9 oz bottles instead of the 8 oz size when they’re four to six months old. Not all baby bottle brands have the 11-ounce available and this bigger size isn’t always necessary. However, if your older baby has a large appetite, the 11 oz bottle can be useful!

Key takeaways

  • Having both 9 oz and 11 oz bottles isn’t always necessary unless your baby has a larger appetite or is going through a growth spurt.
  • Four to six months old babies can switch to 9-ounce bottles while the 11-oz size can be used for infants older than 24 weeks. 
  • Teat sizes may vary for 9 oz and 11 oz bottles depending on the neck width, unique features such as anti-colic vents, and nipple flow rate.
  • Three popular brands that offer both 9 oz and 11 oz bottles include Philip Avent, MAM, and Tommee Tippee. 

Difference between 9 oz and 11 oz bottles 

Feature9 oz Bottle11 oz Bottle
Size (ml)260 ml330 ml
Age4 – 6 months old6 months and older
Feeding quantity4 – 8 ounces per feed7 – 8 ounces per feed
Feeding times6 – 8 feeds/day4 – 6 feeds/day

Do you need both 9 oz and 11 oz bottles? 

Needing both 9 oz and 11 oz bottles is something to consider for various reasons. Once babies reach four to six months old, parents switch over to the 8-ounce bottle. The option of using the 9 oz bottle is available and can be used instead of the 8 oz size. But, how about the 11 oz bottle? 

While not as commonly used as the 8 oz or 9 oz bottles, the 11 oz size is useful if your older baby has a large appetite. Otherwise, sticking with 9-ounce bottles works fine for most bottle-fed babies in their later stages. If you’re pumping breastmilk and looking for larger bottles to store for later use, the 11 oz bottle is a great solution. 

Having both 9 oz and 11 oz bottles is useful for periods of growth spurts when your little one suddenly wants to drink more! 

At what age can a baby start using 9 oz bottles?

Four to six months old is the best age for your baby to use 9 oz bottles. From this age, your baby is drinking bigger volumes, and using the 8-ounce bottle is recommended. However, switching to the 9 oz bottle at four months is an option too. 

At what age can a baby start using 11 oz bottles? 

The best time to start using 11 oz bottles is from six months old. Some parents skip the 8 oz or 9 oz bottle, going straight to the 11 oz size especially if they intend bottle-feeding their babies up to one year or older.  

Are teat sizes the same for 9 oz and 11 oz bottles? 

When it comes to flow rate, the teat sizes are consistent for 9 oz and 11 oz bottles. However, bear in mind that the base width and length of the nipple may vary, and not all teats are interchangeable between brands. 

Depending on the brand you use, find out first how easy it is to get teats for the bigger bottles before purchasing them. Considering design features such as wide-neck vs narrow-neck bottles in bigger sizes will mean different-sized teats.

A quick tip! Getting the right teat size is essential to prevent bottles from leaking and you may be restricted to using nipples designed specifically for the bigger bottle. 

Brands that sell 9 oz and 11 oz baby bottles 

MAM Easy Active Bottles

The MAM Easy Active range is available in both 9 oz and 11 oz sizes. This makes it easy to stick with a brand your baby is happy with if you decide to transition from the 9-ounce to the 11-ounce bottle. 

The Easy Active bottle is great for bottle-fed babies from 4 months old. The design is ergonomic, making it easy for small hands to hold the bottle comfortably while feeding. The silicone nipples are soft and the wide-neck bottle makes it easy to clean them. 

Philips Avent Anti-Colic Bottles

This brand’s anti-colic bottle range comes in both 9 oz and 11 oz sizes. The brand’s unique AirFree vent draws air away from the nipple, reducing the chance of your baby suffering from gas or colic symptoms. The nipples come in different flow rates and are designed to make it easier for your baby to latch. 

The bottles have wide necks and fewer parts, making cleaning them a breeze! Another advantage of these bottles is that you can use them with or without the Airfree vent. 

Tommee Tippee Closer to Nature Bottles

Another popular brand that includes both 9 oz and 11 oz bottles in its range is Tommee Tippee. Its Closer to Nature range comes with silicone, breast-shaped nipples which support the transition from the breast to the bottle. The anti-colic valve reduces air ingestion, vital for babies battling colic, infant acid reflux, or gas buildup.

The bottles are BPA-free, and ergonomically designed for easy holding, and you can get the Y-cut nipple for thickened formula or when adding cereal to the bottle. 

Watch this video demonstrating the benefits of using the Tommee Tippee bottle.


You might have already gone through the task of finding suitable 4 oz or 8 oz bottles, when making the upgrade. That might have been a more simple task. However, regarding the bigger-sized bottles, while most baby bottle brands offer the 9 oz size, not all of them have 11 oz bottles. 

If you’re worried about switching brands, starting your baby on a range that includes both sizes means you can transition to another size if your little one is drinking more. 

I highly recommend picking Avent, Comotomo, and Tommee Tippee dishwasher-safe baby bottles, and nipples if you want to avoid wasting precious time at the kitchen sink! While Comotomo doesn’t have either of these sizes, Avent and Tommee Tippee do and they’re dishwasher-safe too!

Lastly, in this guide I talk about how long you can use bottles of various sizes, typically of sizes up to 8-oz.

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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