Pre-Mixing Baby Formula: What you Need to Know

By: Dr. Nazeli Gevorgyan - April 7, 2024 - 8 Minute Read

Pre-Mixing Baby Formula | The Milky Box

Preparing baby formula is an essential part of caring for your little one, but it can also be time-consuming, especially during those late-night feedings. That’s where pre-mixing baby formula comes in — offering a convenient solution for busy parents looking to streamline their feeding routine.

In this article, we’ll explore how to prepare, store, and handle baby formulas, ensuring you have all the information you need to confidently care for your little one.

Forms of Baby Formulas 

When it comes to infant formula, there are three main forms available: powdered, liquid concentrate, and ready-to-feed. These formulas contain essential vitamins and minerals, typically supplemented with iron as recommended by the American Academy of Pediatrics.

1. Powdered formula: This economical option has a longer shelf life and requires mixing with water before feeding. Simply measure the water and add the powder as directed.

2. Liquid concentrate formula: Packaged in cans or bottles, this sterile liquid form requires mixing with an equal amount of water before use. Unused, unmixed formula can be covered and stored in the fridge, usually for up to 48 hours, offering a balance between convenience and cost.

3. Ready-to-feed: This convenient but more expensive option comes pre-prepared in single-use bottles or larger containers for multiple feedings, eliminating the need for mixing with water. Ideal for on-the-go feeding, it’s gaining popularity for its simplicity.

Forms of Baby Formula | The Milky Box

Making Up Baby Formula

Ensuring safe and accurate preparation of baby formula is crucial for the well-being

of infants. From selecting the right formula to following precise mixing instructions, every step plays a vital role in providing the necessary nutrition for a baby’s healthy development. Next, we’ll outline the necessary steps for preparing baby formula.

Check the Expiration Date 

Prior to preparing the formula, inspect the package to ensure it is in good condition free from any damage or defects that could compromise the quality or safety of the product. Check the formula’s expiration date on the container.

Check the expiration date | The Milky Box

Wash Your Hands

Maintain good hygiene by washing your hands and cleaning the preparation area well to keep your baby healthy. 

Do I Need to Sterilize My Baby's Bottles?  

Before using for the first time, make sure to sterilize bottles, nipples, caps, and rings by boiling them in water for five minutes or using a steam bottle sterilizer. After initial use, typically, sterilization isn’t necessary. Simply wash them with hot, soapy water using brushes or a dishwasher.

However, if your baby is under 3 months old, premature, or has a weak immune system, consult your pediatrician about continuing to sterilize the bottles. For more information on safe cleaning, visit the CDC’s website.

Add Water to Concentrated Liquid or Powdered Formula

Always follow the instructions on the container for the correct formula-to-water ratio unless advised differently by a healthcare professional. Incorrect ratios can lead to under or overfeeding, dehydration, water intoxication, and digestive issues.

In a study comparing infants fed ready-to-feed formula versus powdered formula, those on powdered formula gained more weight, and a higher percentage of them became overweight by 6 months. The study suggests that errors in mixing powdered formula could be the main reason for these differences, emphasizing the importance of getting the formula-to-water ratio right when preparing powdered formula.

Remember to add the powdered or concentrated liquid formulas to measured water, not vice versa. For liquid concentrate, you need to mix equal amounts of water and formula. 

Remember to clean the top of the can and shake well before adding the formula to water.

Using tap water for baby formula is generally safe as long as it comes from a safe and reliable water source. Follow local guidelines and recommendations regarding the safety of tap water for infants. Using filtered or high-quality spring water packaged in glass bottles is the preferred choice.

For infants younger than 2 months old, premature, or with weakened immune systems, it’s recommended to boil water and allow it to cool for about 5 minutes before using it.

Once opened, cover and keep the can of liquid-concentrate formula in the refrigerator for up to 48 hours.

Skip the Water For Ready-To-Go Formula

Ready-to-use formula is already sterile and safe for your baby. It’s crucial to adhere to the manufacturer’s instructions on the label when handling them. Do not add water, other foods (such as cereals), or liquids to premixed baby formula.

Simply clean the top, shake the bottle or container, then pour the formula into a clean baby bottle. After opening, cover the container and promptly store it in the refrigerator for 48–72 hours (as indicated on the label). If you’re using a 2-fl-oz or 8-fl-oz ready-to-use bottle, twist a nipple and ring on, and you’re ready to go.

Formula Preparing Steps | The Milky Box

Can I Prepare Formula Ahead of Time?

It’s generally recommended to prepare baby formula fresh for each feeding to reduce the risk of bacterial growth. Many parents wonder if it’s possible to prepare baby formula ahead of time for convenience. This practice, also known as pre-mixing, can indeed be a practical solution for busy caregivers. 

How Long is the Bottle of Formula Good After Making It?

If you need to prepare a formula ahead of time, for example, for night feedings or traveling, it’s important to know how long it will be safe to use after preparation. Let’s understand.

● Prepared powdered formula that hasn’t been fed to your baby can be safely stored in the refrigerator for up to 24 hours.

● Premixed liquid concentrate formula can be kept up to 48 hours in the fridge, unless otherwise directed on the label.

● Once a ready-to-go bottle of formula is opened or if formula has been poured into bottles in advance, it can be safely kept in the fridge for up to 48 hours.

● Remember, unused formula should not be left out at room temperature for more than 2 hours to ensure safety.

● Once feeding begins, finish the bottle within 1 hour. Don’t save it for later, as bacteria from your little one’s saliva can grow.

● When traveling, a bottle of formula can be kept for up to 4 hours in a cool bag with an ice pack.

Prepared baby formula storage | The Milky Box

Using Pre-Mixed European Baby Formula 

It is essential to remember that most refrigerated prepared formula must be consumed within 24 hours to avoid any health risks. However, the exact duration may vary depending on the specific type of formula. Therefore, it is always recommended to consult the manufacturer's instructions for accurate information.

To assist families in selecting the appropriate baby formula, we have compiled a list of the top-rated European brands recognized for their quality, safety, and nutritional value.

Prepared baby formula refrigerator storage times | The Milky Box

How Do I Warm My Baby's Bottles?

You typically don’t need to warm your baby’s formula, as it’s safe to feed them cold or at room temperature. Avoid using a microwave due to the risk of uneven heating and hot spots that may burn your baby’s mouth.

To warm a bottle safely, you can run hot water over it, place it in a bowl of hot water, or use a special bottle warmer.

How to warm baby bottle | The Milky Box

How to Test the Temperature of Your Baby's Bottle

When warming the formula, make sure to shake the liquid to ensure an even distribution of heat. Before feeding, test the temperature on the top of your wrist to ensure it is comfortably lukewarm, avoiding it being too hot. 

Can I Save Leftover Formula to Give to My Baby Later?

It’s recommended to use the formula within one hour after starting a feeding session and discard any remaining portion to prevent bacterial growth. Reheating formula should be avoided as it can promote bacterial contamination

Pre-Mixed Formula | The Milky Box

How Do I Know Which Recommendations to Follow?

Preparing baby formula in advance can be a time-saving solution for busy parents. However, it is important to follow proper guidelines to ensure the health and safety of your baby. This includes using clean bottles and utensils, and taking extra precautions to store the formula safely.

When deciding on the best way to prepare and feed your baby formula, it is always best to rely on trusted sources. This can include guidance from the formula packaging instructions, advice from your medical provider, and recommendations from healthcare organizations.

If you're looking for access to high-quality European formulas and reliable information on preparing and feeding your baby, you can reply to The Milky Box.


Please be aware that this information is based on general trends in babies, and it is not medical advice. Your doctor should be your first source of information and advice when considering any changes to your child’s formula and when choosing your child’s formula. Always consult your pediatrician before making any decisions about your child’s diet or if you notice any changes in your child.

Breastfeeding is the best nutrition for your baby because breast milk provides your child with all the essential nutrients they need for growth and development. Please consult your pediatrician if your child requires supplemental feeding.

Nazeli Gevorgyan is a medical doctor from Armenia, and is a researcher in the fields of Obstetrics and Gynecology, among others. Dr. Nazeli is passionate with providing women and parents with reliable and high-quality information on healthy options for infant nutrition, breastfeeding, infant formula, and food. In her free time, she enjoys swimming, traveling, and pottery. 

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Reviewed by Suzanne Renee',

Infant Nutrition Expert

Suzanne Renee' is an accomplished professional with extensive expertise in the area of infant nutrition, dedicated to promoting the health and wellbeing of children. She started this journey as a foster parent.

Suzanne has emerged as a strong proponent of the European baby formula and has become a full-time writer on the subject. 

In her free time, she enjoys camping, hiking, and going to church.