Bottle Warmer vs Hot Water vs Microwave Explained

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While some babies are happy to drink formula or expressed breastmilk at room temperature (or sometimes even straight from the fridge), a lot of babies prefer their bottles warmed up.

But what’s the best way to heat up a baby’s bottles?

Parents have three main options:

  • A bottle warmer
  • Sitting the bottle in hot water
  • And the microwave

Using the microwave to heat a baby bottle is NOT recommended — you’ll understand why by the end of this article.

But overall, what’s the difference between a bottle warmer vs hot water vs the microwave?

Electric bottle warmers are extremely effective and convenient — however, when you already need to buy a million things for a new baby, they can be an unnecessary expense.

Using warm water to heat up a bottle works just fine if you can spare a few minutes. If you can afford one, however, having a bottle warmer on hand will come in handy when you’re in a hurry.

Bottle warmerQuick, heats to perfect temperatureWon’t fit all bottles, expensive
Bowl of warm waterFree, won’t overheat milk or bottlesTakes several minutes
MicrowaveFastNot recommended by the FDA due to burn risk

Once you’ve decided which method is likely to work best for your family, remember to add any equipment that you’ll need to your newborn shopping list.

Let’s take a closer look at all of your options.

Pros and Cons of Bottle Warmers

A bottle warmer is a simple piece of countertop equipment that gentle heats a bottle of milk to the desired temperature.

Some parents swear by bottle warmers and use them many times each day.

Whereas others might buy one and then let it gather dust at the back of the cupboard.

You won’t know which camp you fall into until your baby arrives and you get into a routine.

To help you decide whether to invest in a bottle warmer or not, let’s take a look at some of the pros and cons of using electric bottle warmers to heat milk. 


Perfect temperature control: Reaching the correct temperature is easy with a bottle warmer as they heat baby milk to the ideal temperature every time. That means no constant checking to see if it’s warm enough, or too warm.

Preserves nutrients in breastmilk: Overheating breastmilk destroys some of the vitamins and minerals. The best bottle warmers never heat the milk to this level, so you can be sure that your baby is getting 100% of the goodness.

Safety: Bottle warmers are considered safe to use as there’s no chance of burning yourself or your baby with hot water or overheated milk.

Easy to use: Simple bottle warmers have just one switch, making them super simple to use. This is handy if you want a grandparent or older child to help out while you’re busy.

Fast: Bottle warmers only take a couple of minutes to heat up the milk. If you choose one that beeps when it’s ready, you’ll waste no time hanging around waiting for it.

Can be portable: While many electric bottle warmers are bulky and need to be plugged in, you can also get portable, battery-powered bottle warmers. Some travel bottle warmers need to be filled with hot water – they’re essentially just a fancy flask.

Multi-functional: The most hi-tech bottle warmers can also be used to heat baby food once your little one moves on to purees. They may also be able to sterilize clean bottles for you.


Not all bottles fit: Not all types of baby bottles fit into every bottle warmer. Some bottles are too tall or too wide. Make sure you check that yours are compatible before you make a purchase.

Can be expensive: Top-of-the-range bottle warmers can cost upwards of $50. While some electric bottle warmers cost as little as $20, if you opt for a cheaper brand you’ll need to pay close attention to the reviews to be sure that it does what it’s meant to.

Chance of malfunction: Any electrical appliance can have problems, so you should never put your trust in a bottle warmer to heat the milk properly. If the temperature regulation feature fails, the milk could stay cold or overheat. Always check the temperature of the milk on the back of your hand before offering it to your baby.

Smell: Some parents have reported that their bottle warmers release a nasty smell when heating the milk, despite thoroughly cleaning them.

If you’re not sure a bottle warmer is worth the hassle or investment, you can always do what parents have been doing for decades — placing the milk bottle in a bowl of hot water for a few minutes to warm it up!

Pros and Cons of Sitting Bottle in Hot Water

Heating baby milk by placing the bottle into a jug of warm water is a traditional method that’s been used for generations and is still very popular.

It can be used for both breastmilk and formula, that’s at room temperature, chilled, or even frozen.

Using hot water to heat baby bottles can take a little bit of practice. Here are some of the pros and cons of this method…


Requires no special equipment: You can get hot water from the tap, kettle, microwave, or stovetop and use any kind of jug or bowl that you already own to place the bottle in.

Good for on the go: Carrying a flask of water is easy and means that you can heat milk on the go. Most cafes and restaurants are also happy to give out a jug of warm water if you ask nicely.

Free: As you don’t need to buy anything, there’s no cost to this method.


Slow: It can take several minutes to warm the milk to the desired temperature, which is less than ideal when you have a screaming, hungry baby.

Chance of scalding: While very hot water will work faster to heat the milk, this increases the risk of burning yourself if you accidentally spill some on your skin. It can also heat the milk to too high a temperature. If you use warm or hot water from the tap, it’s very unlikely you’ll overheat the milk or risk any sorts of burns.

Can destroy the nutrients in breastmilk: Heating breastmilk to over 104°F will begin to damage the nutrients. Of course, it’s tricky to know exactly how hot the water that you’re using is.

Hard to control temperature: It can be tricky to know when the milk is warm enough, so you’ll likely have to test it a few times to make sure it’s not too hot or too cold.

If you like the idea of saving money by using equipment you already own, but want a faster bottle heating option, you might think using the microwave makes sense.

But let’s take a closer look at why the microwave isn’t recommended by doctors and pediatricians.

Pros and Cons of Warming Bottles in the Microwave

When we were babies in the 80s and 90s, using a microwave to heat baby milk was acceptable.

But then so were a lot of things, like smoking cigars in hospitals and riding in a car without a seatbelt!

Nowadays, experts recommend that parents avoid using a microwave to warm baby milk because modern studies have shown that microwaves heat breastmilk and formula unevenly.

This can result in ‘hot spots’ which can burn your baby’s mouth or throat.


Quick: A microwave oven may be the fastest way to heat milk, which is tempting when you have a very hungry, crying baby.


Not recommended: The FDA advises that “heating breast milk or infant formula in the microwave is not recommended.”

Destroys the nutrients in breastmilk: As microwaves heat unevenly, areas of breastmilk will almost certainly become too hot, which will reduce the vitamin and mineral content of the milk.

Unsafe: There are many things that can go wrong with using a microwave to heat breastmilk, including exploding bottles, scalding your hands, and hot spots in the milk.

If you do decide to use a microwave, here are some tips to reduce the risk.

Wrapping Up

While there are three ways to heat baby milk, the microwave method isn’t recommended because it is considered to be unsafe. 

That leaves you with the electric bottle warmer option or the old-fashioned method of sitting the bottle in warm water.

If you intend to breastfeed, you may only need to warm bottles occasionally, so it might be worth holding off on the purchase of a bottle warmer.

If you intend to use formula, you may find that your baby is happy with room-temperature milk when you’re out and about.

While there’s no harm in adding a bottle warmer to your newborn shopping list — they can be quite convenient and useful — if you’re short on cash it might be wise to wait until you’re sure that it’s something that will make your life easier. 

In other words, bottle warmers are a useful luxury but not at all a necessity for bottle feeding.

Before you go, don’t miss these feeding guides:

Hope this helps!