How To Keep Baby Bottles Warm On The Go

Keeping your baby’s bottles warm on the go is something that most parents ask about. Unfortunately, there isn’t a simple, one-size-fits-all, cut-and-dry answer, and guidelines can sometimes be hazy.

Parents follow the science when preparing or heating baby bottles to the right temperature, or do they?

Keeping bottles at the optimum feeding temperate is a gauntlet that many moms or caregivers face, at least for the first 6 months of a baby’s life. There are a few safe methods to keep baby bottle milk at the ideal feeding temperature, 37 C (98.6 F), the normal temperature of breast milk.

We look at heating baby bottles and ways to keep them warm for on-the-go feeding.

What does the science say?

The temperature is important whether you are warming up refrigerated breast milk or making a new formula bottle.

As mentioned, the temperature of breast milk direct from mom’s breast is 37 C or 98.6 F, which is our normal body temperature.

Breast milk heated slightly higher than 40 C, or 104 F, begins to lose its nutritional and immunological value, and this is where many parents ignore the science in their rush to heat their baby’s bottle.

We all know that keeping any liquids at a set temperature using a thermal flask or bottle warmers is the way to go, but the contents gradually lose heat.

Keeping water warm to make a formula feed is easy because you’re dealing with pure water and not an already mixed formula milk bottle. On the other hand, breast milk can be safely chilled or even frozen and brought up to the correct feed temperature without any value loss. It’s the higher temperatures that matter.

Body temperature (37 C, 98.6 F) is considered lukewarm by adult standards, and baby bottles should not be heated above this ideal feed temperature.

Let’s take a look at our perception or understanding of temperature:

100 C or 212 FBoiling point of water
60 C or 140 FScalding hot
48.88 C or 120 FThe standard temperature of most home hot water heaters. High enough to substantially degrade the value of breast milk.
40 C or 104 FNormal temperature for hot tubs. This is already too hot to warm breast milk.
37 C or 98.6 FBody temperature. Also, the ideal breast milk and feed temperature.

Are higher temperatures not a concern for formula milk, you might ask? According to formula mixing instructions, the water should be 37 C (98,6 F) when added to the formula.

To get rid of bacteria, you need to boil the water and keep it boiling for at least a minute before taking it off the stovetop. You then need to let the water cool to the correct feeding temperature before adding it to the formula.

Formula milk will be safe for an hour after it is mixed, and any left-over milk after feeding should be discarded to prevent bacteria growth. This is very important for infants younger than three months old.

When on the go, you can use a thermal flask and fill it will water slightly hotter than 37 C (98.6 F). It should be at the right temperature within a few minutes.

Test the temperature with a few drops of water from your baby’s bottle on the inside of your wrist before you mix the formula.

The science for practical purposes is tied into nature as far as breast milk is concerned, and for formula, the answers lie in the instructions printed on the packaging. Yet many parents still fumble with the basics; why?

Bottle heating mistakes

Dad is warming up a bottle of milk for his newborn son.
  1. Heating breast milk or formula in a microwave is a definite no-no! Not only do microwave ovens heat unevenly, causing hot spots, but they also break down the nutritional value of milk or food items being heated.
  2. Using scalding hot water, either from a boiled kettle or your hot tap is also not advisable to warm up your baby’s milk faster. The heat will affect the milk closest to it, and even if you swirl the milk around in the bottle to distribute the heat, there is still damage being done.
  3. Mixing formula with water above 37 C (98.6 F) is not recommended. Although a slightly higher temperature may still be fine (please fact check this), it means you will have to cool the milk before your little one can feed. Remember, there is a safe period of one hour from when feeding starts before the formula becomes unsafe for use. From mixing, you have a two hour period at room temperature before the formula is no longer safe.
  4. If milk is heated too high, it can burn your baby’s mouth and throat, leading to feeding complications or worse.

Slow and steady wins the race 

If you’re a mom with experience or a first-time mom, you will all value the effort you put into being prepared for all eventualities, feeding your little one included. You will know that being prepared is already half the race won, and your tiny bundle of love will always be better off through your caring thoughtfulness.

We’ve run through some quick-fix bottle warming “solutions” that I’m sure most of us have tried at one time or another because, let’s face it, we’re not perfect, but we sure do try. Now, let’s look at how we can get bottle warming right every time.

It’s important to get into sync with your little one’s feeding pattern, so you don’t respond to every cry with feeding as a solution.

Soothing tends to help for long enough to prepare a bottle, and because you have prepared in advance, it won’t take you long to have a bottle ready. As a mom, you will know when your baby is hungry and having everything ready makes for a happier baby.

Stick to warm water (not hot) to heat breast milk to the correct feeding temperature. There are many different types of bottle warmers on the market, and it’s always a handy gadget to have around.

You can also use a thermal flask to keep the water warm for formula, and there are great flasks that maintain temperature for hours on end.

Formula stack containers (usually in a stack of three containers) are also very handy and a great time-saver too. You measure the formula per feed at home, and each container will have the exact amount required to make a bottle.

You may also wonder why it’s necessary to warm bottles on an ongoing basis. Well, to be honest, it’s not necessary, but it may be how your little one prefers their milk served. Initially, milk at 37 C (98.6 F) is what compliments a newborn’s fragile digestive system, but as your little one gets older, you can offer milk at room temperature or slightly warmer.

If your baby shows no objection to normal room temperature milk and has no signs of bowel irritation, you no longer have to worry about heating the milk.


Can I refrigerate left-over bottled milk and reheat it for a later feeding?

No. Bacteria from your baby’s mouth/saliva will contaminate the milk and will begin growing even if refrigerated.  The heat required to kill bacteria in milk is very high and will also destroy nutrients.

Why is formula not safe after 2 hours at room temperature?

According to CDC guidelines, bacteria will grow in formula milk after two hours at room temperature, making it unsafe for your baby. If refrigerated, it can hold for 24 hours but must be used within this period.

Why is warm milk better for babies than milk at room temperature?

Breast milk is at body temperature and is much easier for babies to digest. Formula or pumped breast milk can be served at room temperature, but your baby will use more energy to digest it. Room temperature milk may cause tummy craps in younger babies, and warming the milk will help to alleviate this problem.


If you are not breastfeeding, heating your baby’s milk to 37 C (98.6 F)  is advised for newborn babies and may be necessary for the first three months or perhaps a little longer, depending on your baby’s preference and health.

Weaning your baby off warm milk to room temperature milk should be a slow, gradual process that should be measured by your baby’s response to cooler milk. Both breast milk and formula milk below body temperature are fine for your baby, so there is no need to stress, but just make sure the milk is never too hot.

Heating milk before feeding should be done with warm water that doesn’t burn your skin. You should be able o comfortably immerse your hands in the warm water.

Alternatively, using a bottle warmer, whether home-based or portable, will warm your baby’s milk up to the correct temperature within minutes.

Always check the milk temperature on the inside of your wrist or back of your hand to make sure it is safe for your little one.  

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Hi! I'm Jennely. My hands and mind can't be still; neither can my three-year-old. So I'm either chasing him or my next project. I like to work smarter, not harder. This is why I write on topics that will help parents solve problems and enjoy precious moments with their little ones.

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