Bottle Warmer vs Prep Machine (e.g. Baby Brezza) – Need Both?

Balint Horvath, PhD

Writer, parent, and veteran of baby feeding battles.


Wondering about the most effective way to prepare or warm your baby’s bottle using a bottle warmer vs a prep machine? Can you only use one or the other? Do you need both? Keep reading as I answer these questions.

Since warmers and prep machines do completely different things, consider each one’s function. Bottle warmers will only warm up ready-made bottles. Prep machines on the other hand will mix formula to the correct temperature or boil water to the required temperatures. 

Key takeaways

  • Bottle warmers are ideal for warming formula, frozen milk and even food in jars. 
  • Most bottle warmers are compatible with all leading bottle brands. 
  • Prep machines are pre-programmed to mix and warm the formula in about 2 minutes. 
  • Unlike bottle warmers, prep machines can’t warm frozen milk.

Bottle warmer vs prep machine comparison table

When deciding whether you need a bottle warmer or a prep machine, it’s helpful to compare the key features of both. 

FeaturesBottle WarmersPrep Machines
Prepare formulaNoYes
Warm frozen milkYesNo
Time taken to have a bottle ready4 – 6 minutes2 minutes 
Can warm foodYes, if the food jar fits in the warmerNo
Best for Warming frozen breast milk, formula and waterMakes formula from scratch and can heat water

Bottle warmer vs Baby Brezza

Since the Baby Brezza is such a popular model, parents frequently enquire about the key differences between the bottle warmer vs Baby Brezza

Baby Brezza New and Improved Formula Pro Advanced Formula Dispenser Machine - Automatically Mix a Warm Formula Bottle Instantly - Easily Make Bottle with Automatic Powder Blending, White

The Baby Brezza Pro Advanced Formula Dispenser is one of the top formula prep machines and it’s quite easy to see why. With this machine, you can make a warm, formula bottle instantly. There’s no need to measure or mix the formula beforehand. 

Simply fill the machine with dry formula, pre-program bottle requirements between 2-10 ounces and choose 1 of 3 temperature settings. It’s a very quick and easy way to make baby formula, and is a dream for parents who primarily do formula-feeding. 

Here’s a short clip that highlights the features of the Baby Brezza. 

Bottle warmers, such as the Philips AVENT Fast Baby Bottle Warmer don’t pre-make the formula – you will still need to do that before using the warmer. However, you can either make formula with cold water or use room temperature water and then use the unit to warm milk in just 3 minutes. 

Philips AVENT Fast Baby Bottle Warmer with Smart Temperature Control and Automatic Shut-Off, SCF358/00

The unit will also keep the milk warm for an additional hour inside the unit before shutting off. Bottle warmers are an excellent option for moms who are breastfeeding and would like to warm frozen or stored breast milk. 

If you’re more likely to use a bottle warmer, this clip illustrates how easy it is to use the Philips AVENT Fast Baby Bottle Warmer.

How a bottle warmer works

Bottle warmers are very handy and can simplify feeding in a hurry. It’s a quick and safe way to warm both formula, colder breast milk or even food in a jar. The only criterion for warming is that the bottle or jar should fit into the warmer. Here’s how they generally work. 

  • Prepare your formula bottle or place frozen breast milk into the required bottle. 
  • Add water to the pot
  • Place inside the bottle warmer.
  • The warmer then heats up the water and circulates, ultimately warming the milk or formula. 
  • Some warmers can keep bottles warm for up to an hour before switching off.

If you have twins, you’ll need twice as much milk warmed in a hurry. My article about the top bottle warmers for twins and triplets is a must-read!

How a prep machine works

In short, a prep machine works on the same principle as your espresso or cappuccino machine. In addition to the Baby Brezza, there’s also the Tommee Tippee Perfect Prep that’s another firm favorite among parents who are formula-feeding. 

Tommee Tippee Perfect Prep - Máquina de preparación del biberón, color blanco

Both the Baby Brezza and the Tommee Tippee Perfect Prep work using the same concept, as listed below:

  • Place your formula of choice into the top of the machine.
  • Pre-program the machine to make your preferred quantity.
  • Add water to the unit.
  • The machine mixes, warms and dispenses the formula.
  • Remove the bottle and serve it to your little one. 

Pros and cons of a bottle warmer


  • Some brands can keep the bottle warm for a period after being switched off.
  • Steam heats the milk ensuring even heating.
  • Faster than stove or microwave warming. 
  • Suitable for warming formula and breast milk.
  • Most warmers can accommodate leading bottle brands.
  • Can also warm baby food if the food jar fits into the warmer. 


  • Can take longer to warm frozen milk.
  • Does not make the formula. 

Pros and cons of a prep machine 


  • Prepares formula from scratch.
  • Custom settings. 
  • 10x faster than a kettle. 
  • Preserves nutrients.
  • Filter system removes impurities present in water.


  • Can’t warm up frozen breastmilk.

Do I need a bottle warmer if I have a prep machine?

If you are freezing your breast milk, you won’t be able to warm the milk in a prep machine. Essentially, prep machines can only prepare and dispense mixed formula or boil water to the correct temperature. This means, if you are focused on feeding your baby breast milk only, you will still need a bottle warmer.

Do you fill the prep machine with cold water?

The Brezza Baby Prep should always be filled with distilled water to avoid mineral scale build-up. Using distilled water means you can use cold water. Manufacturers recommend boiling tap water first.

Placing cold water in the Baby Brezza means the unit will take between 10 to 20 minutes to warm the water. Hot water will obviously result in warm water a lot quicker. 

Can you use any bottles with a prep machine and bottle warmer?

When shortlisting a potential prep machine, always check if it’s compatible with the bottle you’re using. This matters because your bottle needs to fit under the spout. Fortunately, the Tommee Tippee Perfect Prep Machine can accommodate all formula bottles. 

Not all bottles work with all bottle warmers. As with the prep machine, you will have to check the shape and length of your bottle. 

Keep in mind that some manufacturers warn against using glass bottles in warmers. However, the GROWNSY 8-in-1 Warmer is compatible with most leading bottle brands. This is why I keep recommending this product on my blog.

Which machine should you choose?

As I’ve already mentioned, whether you opt for a warmer or prep machine depends on your personal preference. A prep machine is an excellent choice if someone other than the primary caregiver is looking after the baby so you avoid the situation when your baby refuses the bottle from anyone except for mom.

You can pre-program the measurements and temperature in advance. This will give you peace of mind that your little one is getting the right amount of formula at the correct temperature.

On the other hand, if you already have pre-packed milk storage bags, the bottle warmer will be all you need to warm your bottles to the right temperature. Read about the best ways to warm your baby bottles.


Both bottle warmers and prep machines can make the baby feeding process considerably easier. Opt for the prep machine if you’re formula-feeding as you can pre-program it to make the right amount. A bottle warmer is better suited if you need to defrost and warm frozen breastmilk. 

If you’re interested in bottle warmers, I recommend that you read my articles about the best bottle warmers for different bottle brands or specifically bottle warmers for Comotomo are recommended.

Last update on 2024-04-07 / Affiliate links / Images from Amazon Product Advertising API

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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