Skip to Main

Pumping breastmilk is often full of questions. This guide will help you make it a bit more simple when it comes to storing and using that precious liquid gold more efficiently.

Every pumping person will find their own groove with their pump of choice and their own body’s output. Remember that there is a wide range of normal and filling an entire bottle from one pump session is less common.

How much breast milk should I pump for feeding and storage?

Woman holding breast pump

Depending on your baby’s age and needs, they likely won’t need a lot of milk in each feeding. KellyMom, a go to resource for breastfeeding information, has a helpful guide to figure out your own baby’s needs. According to research, most babies take in between 19 and 40 ounces per day, depending on how many times a day they are fed and age.

For infants, I find that freezing smaller amounts is better to reduce potential waste. Freeze 2-4 ounces in a storage bag and then combine if more milk is needed. This way you don’t defrost more than you need and end up dumping milk down the drain. For older babies who you know consistently drink larger quantities, you can freeze more in an individual bag.

Step by step guidelines for storing your breast milk

Medela breast milk funnel

Image Source:

Once you’ve pumped a few ounces, pour the milk into a storage bag. If you’re using a pump with a removable flange, like Medela, you can even use it as a funnel to make the transfer easier.

Some pumps also work with an adapter to pump directly into a breastmilk storage bag to minimize transfer loss and clean up. Let’s maximize those drops of milk! Label the bag in permanent marker with the date and ounces pumped.

Pro tip: use the ounces marker on the bottle and not the bag as those tend to be off. The key to optimal storage is to place the bag flat in the freezer. This allows the milk to freeze into the most compact packet.

Women store breast milk in freezer

Once frozen in a flat packet, store the milk in the back of the freezer. The freezer door is the least reliable place to store breastmilk as it may risk premature defrosting. The back of the freezer or a deep freezer will keep the milk frozen safely for longer periods of time.

Use a shoebox, plastic bin, empty soda box, or other similar container to place the frozen milk packets for easy access. Place the most recently pumped milk in the back, using the “older” milk first. I imagine them being stored like an old school library card catalog.

By storing milk this way, you maximize space, simplify the process, and make it easier for other caregivers to easily access the right amount of milk for your baby.

How to warm frozen breastmilk

Hot water from kitchen faucet

To defrost and warm breastmilk, you can use an electric bottle warmer or simply a bowl of hot water. Simply place the frozen breastmilk bag in the water and allow the heat to warm the milk.


The ideal temperature for milk is body temperature. Once you pour the warmed milk into a bottle, swirl, do not shake the bottle, to combine. When stored, breastmilk naturally separates with the fat coming to the top. Swirling will combine it gently without disturbing the composition.

Combining milk from different breastfeeding sessions or different storage bags is safe. If combining freshly pumped milk, allow both to either come to room temperature or both to cool (get them to similar temperatures) and then combine.

How long can I store breast milk?

For a full term, healthy baby there are some general guidelines for safe storage of expressed breastmilk. If your baby is not a full term, healthy infant, please discuss guidelines and recommendations with your pediatrician and a lactation consultant.

See the breastmilk storage chart below for more details.

FRESHLY EXPRESSED Temperature (Fahrenheit) Storage Time
Warm Room 80-90 3-4 hours
Room Temperature 61-79 4-8 hours, ideal 3-4 hours
Insulated cooler/ Ice packs 59 24 hours
Fresh Milk 32-39 3-8 days, ideal 3 days
Thawed Milk 32-39 24 hours
Interior freezer compartment varies 2 weeks
Self contained freezer unit <39 6 months
Separate deep freezer 0 12 months, ideal 6 months
*source Kelly Mom

When is it time to toss breast milk?

Trash cans

The decision to pour breastmilk down the drain can be a tough one. I get it! You worked hard for that milk! But sometimes, dumping milk is the safest choice for your baby.

If breast milk has exceeded the above storage guidelines, it is suggested not to use the milk for consumption. If the milk has been in a fridge or freezer that has lost power for an extended period of time, it may no longer be considered safe. In this situation it may depend on the type of storage (fridge/ freezer) and how long it has been without power.

In a freezer, if the frozen milk still has ice crystals, it may still be safe to use. If pumped milk smells sour or rotten, it may not be safe to use.

For some lactating people, they may have high lipase. Lipase is an enzyme in breastmilk. When frozen breastmilk with high lipase is defrosted, it may have a soapy smell. This milk is safe for consumption, although some babies may not take it. There are tips for remedying this without dumping milk!

By: Erin Pasquet
Birth and Postpartum Doula
Childbirth Educator
Certified Lactation Counselor
Pre/Post Natal Yoga Teacher