When nursing babies with baby formula: it may often seem like you never have enough. Babies eat often – their tiny stomachs can only hold so much at once. When your little one constantly wants another bottle, it can be tempting to make a large batch of baby formula and have a few days’ worth ready to go. However, this is not the right idea to have simply because baby formula doesn’t last all that long before going bad. Besides, how often do you thoroughly enjoy your day’s worth of meal prep? 

In such a case, this question arises ‘how long does the prepared baby formula last?’, and how can you stretch things to make the most of a big batch? For all the mom’s wondering what a best practice is, you can find the answer by reading on. 

It Depends On the Type and Whether You Refrigerate

All baby formulas have a set expiration rate, that depends on the type of container the formula is stored in as well as the form that the formula comes in (liquid or powdered). 

In terms of spoiling point, that depends on the length of time that the formula stays at room temperature. 

It’s a great rule of thumb as well as a recommendation from the CDC to never prepare a bottle of formula more than 24 hours ahead of time, especially if you are using powdered formula. Also, any bottle of formula you make should either be immediately fed to your baby or be refrigerated for up to 24 hours.

But, how long does baby formula last?


Most baby formula brands offer formula in powdered forms. Powered formula must be mixed with water to create the final formula substance. Being a product derived from a cow’s milk as a base, powdered formula (and all other types of formula, for that matter) operates within the same expiry limits as other milk products. This means that extra care and attention must be paid to storing formula that has been prepared i.e mixed with water. 

Room Temperature: baby formula lasts for about two hours at room temperature. However, if you warm the baby formula from the fridge, you should only keep it for about an hour then it must be discarded. 

Refrigerated: baby formula lasts for up to 24 hours once refrigerated at a temperature set to between 35°F and 40°F.


Although infant formula concentrate and ready-to-use products have different forms, they’re still derived from a base of milk protein. So, their spoilage rates are largely the same.

Room Temperature:  infant formula lasts 2 hours if kept at room temperature, and only an hour if you warm the formula up post refrigeration.

Refrigerated: infant formula will last for about 48 hours with the same refrigeration temperature setting mentioned earlier: between 35°F and 40°F.

What About Expiration Dates?

The expiration date printed on the outer container of your baby formula -usually marked by ‘best if used before …’  refers to when the base product will no longer be good for use. It doesn’t refer to the formula once it’s been turned into a liquid form. 

For instance, a container of baby formula sold as a powder may have an expiration date for a year from the date of purchase. This means the powder is only good for a year’s time, especially after you break the seal and expose the powder to environmental cues.

 It does not mean that the baby formula you make with the powder mixed with water lasts for 30 days. Once mixed or activated – baby formula is only good for 24 hours – no more. 

Why Does Formula Only Last for a Short While?

Baby formula lasts for a short while because these products are milk-based and as such, they can go sour.

Milk is often in an environment that allows for bacterial growth. All milk-based products contain lactose, which is a type of ingredient that’s ideal for bacteria to eat. The milk’s protein environment provides a place for bacteria to thrive and multiply. This is why, if you put milk out on the counter for too long, it quickly turns sour and gains a foul taste and smell.

Can You Re-Refrigerate Partially-Used Bottles?

No, once you begin feeding and your baby discontinues, leading to partially-used formula it must be discarded – usually within one hour. After you use a bottle to feed your little one, it’s already provided an opportunity for bacteria to settle and grow especially when saliva is combined. 

Milk or formula consumed within appropriate times does not face this problem, as it’s digested by the stomach and intestines. If you refrigerate the formula after partially using, bacteria may go into temporary hibernation but could still multiply over time. Furthermore, they could turn the formula sour while in the refrigerator. By warming up that said bottle of formula, you may be giving bacteria a chance to grow once again, which can be disastrous for your baby’s stomach.

Remember, infants don’t have as robust systems as adults. Giving them sour milk or formula may present a cause for concern. 

This basic principle is why the timeframe for the formula that you warm up instead of making and serving at room temperature is a little shorter. Warm milk or formula is an even better environment for bacteria to thrive. 

Can You Freeze Formula?

You can, but there isn’t much of a point. Frozen formula won’t have any issues with bacteria, of course. But you’ll end up having to spend more time and energy thawing the milk out to about room temperature or a little above for it to be suitable for your baby to consume.

You should never microwave your formula, as this can create small hotspots or bubbles within the formula product. Your baby might then get a scalded tongue or throat by accident and we don’t want that.

Once thawed, the formerly frozen formula has the exact same expiry rate as regular milk that you had in the refrigerator and warmed up correctly. In the vast majority of cases, it’s simply easier to make a new baby’s bottle at the right temperature. 

What’s the Best Way to Warm Bottles of Formula So They Last the Longest?

If you refrigerated your baby formula – sticking with the guidelines shared above then you can serve it to your baby one of two ways. Baby formula may be served straight from the fridge or warmed to safe levels. It is completely up to you and what your baby prefers. 

If you choose to warm the formula, here are some ways to do so:

  • Run your bottle of formula under hot water for a few minutes.
  • Put the bottles in a pan of warm boiled water.
  • Use a separate bottle warmer designed specifically for this purpose.

Whatever way you choose to do this, you’ll want to shake your bottles up to mix formula and make sure that the heat is attributed evenly. Always test any warmed-up formula by putting a few drops on the inside of your wrist before feeding it to your baby. If the formula is too hot for comfort, it needs to be cooled for a few minutes- you can do this by running cold water on the bottle. Lukewarm is the ideal temperature for feeding.

What’s an Ideal Baby Formula Preparation Schedule?

Of course, having enough formula on hand all the time can be tricky given how quickly it seems to go bad. As mentioned, it’s a good idea to only prepare enough formula for the following 24 hours.

You can also consider how frequently your baby feeds and plan things out. In the earlier months, babies usually eat every 2 to 3 hours or 3 to 4 hours depending on their appetite. This may necessitate between four and eight bottles every day, which you can make the night before and refrigerate so they’re ready to go.

The key is planning and scheduling. Figure out how frequently your baby eats, then make enough bottles for that purpose. You can even make an additional bottle in case they become suddenly hungry or are going through a growth spurt. Even if you have to throw the bottle out if they aren’t hungry, it’s usually better to do that than serve your baby formula made past the 24-hour mark. 

Plus, making your baby formula can be a quick process, so you can make a fresh bottle before each feeding. 

Using boiled water: The water used only needs to be boiled for 1-2 minutes and you can cool to room temperature within 30 mins before making the bottle.

 Using room temperature water without boiling: according to the AAP, using room temperature water without boiling is fine for making baby formula. Once tap water is safe (according to your health department), it does not need to be boiled – if it is not safe or you are unsure or even rather not use tap water then you can use bottled water at room temperature.  

Do Other Types of Formula Last the Same Amount of Time?

Yes, other formulas last the same amount of time. While soy-based or goat-milk-based baby formula products are slightly different in terms of their taste and texture, they’re still milk-based products. While it’s technically true that soy-based baby formula might not be as sensitive to bacterial souring, it’s still quite capable of being soured very quickly. In most cases, it’s still smart to just adhere to the 24-hour or 48-hour rule for simplicity.


This article aimed to provide an answer for the question: How long does baby formula last? All in all, it was stated that baby formula only lasts for about a day refrigerated, and only for about an hour or two at room temperature. This can make preparing baby formula with any regularity a bit of a challenge, which we understand.

For our part, we recommend setting aside a little bit of time every day to prepare baby formula so that everything is always fresh and ready to go and isn’t in danger of spoiling or souring. 

Feeding with formula gives you a little extra convenience but in exchange, you will need to put in a little more prep time and consideration. The great thing is that using room temperature water that hasn’t been boiled is a good option as well as 24- hours is quite a long time.  

With the right mindset and a good schedule, it’s totally possible to come up with a feeding and formula prep routine that works for your needs. If you’re having trouble, that’s what we’re here for! Let us know how we can help or reach out for more tips and tricks when it comes to feeding your baby with formula.

Bridget Reed, contributing writer for Milk Drunk with the expert advice of Dr. Jacqueline Winkelmann, board-certified pediatrician awarded Top Pediatrician by the International Association of Pediatricians: Leading Physicians of the World in 2018.

Bridget Reed is an experienced writer, editor, and SEO content manager. She graduated with her bachelor’s in business management and organizational leadership and is a proud mom of three.

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