Freeze It Flat™

How to Store Breastmilk in the Freezer: A Complete Guide + Why Freeze It Flat Is a Game-Changer

Storing breastmilk in the freezer can feel overwhelming. You want to preserve every drop, make it safe, make space, and make it convenient when you need it. As a pumping mom (or soon-to-be mom), getting this right can save you time, stress, and milk.

In this post, we’ll cover:

• Why freezer storage matters
• Safety guidelines (how long, what temperatures, containers)
• Common mistakes and how to avoid them
• How to organize and stack your freezer stash
• Why Freeze It Flat from MILKworx is such a helpful tool
• Tips and resources to make your freezing routine smoother

Why Freezer Storage Matters

Whether you're building a freezer stash, supplementing feeds, going back to work, or just want peace of mind, breastmilk in the freezer gives flexibility. But if it’s stored poorly, you can lose space, waste milk, or risk compromising quality.

Some of the key reasons to pay special attention:

• Maximize usable freezer space. Bulky or oddly shaped milk bags waste space and make it hard to organize.
• Preserve milk quality. Proper freezing, storage, and thawing prevent nutrient loss or spoilage.
• Safety. Reducing risk of contamination and bacterial growth.
• Convenience. When milk is easily accessible and well organized, feeding (or thawing) is simpler, faster, and less frustrating.

Safety Guidelines: What Experts Recommend

Here are recommended best practices for freezing breastmilk safely:

ItemBest PracticeContainer typeUse breastmilk storage bags or containers made specifically for freezing human milk. They should be BPA-free, leak-proof, and seal tightly.LabelingAlways label with the date pumped. Use oldest milk first (“first in, first out”).Freezer temperatureStore in a deep freezer (0°F / −18°C or colder) for long-term use. If using freezer compartments inside a fridge, make sure temperature stays consistently cold.Storage durationFor deep freezers: up to6–12 monthsis acceptable, though using within 6 months ensures best quality. For standard household freezers: up to3–6 months. Always check local or health guidelines.ThawingThaw in refrigerator, or under warm running water. Avoid microwaving or boiling, which can destroy nutrients or create hot spots.RefreezingOnce fully thawed, do not refreeze. Use thawed milk within 24 hours if kept refrigerated.

These guidelines help maintain nutrition, avoid spoilage, and keep your milk stash safe.

Common Mistakes to Avoid When Freeing Breastmilk

Counting on these will help you preserve more milk and avoid frustration:

1. Freezing in bulky or uneven shapes
   Bags that settle into irregular lumps or are half-filled freeze unevenly, take more room, and thaw more slowly.
2. Overfilling bags
   If liquid expands when frozen, overfilled bags may burst or seal poorly.
3. Not expelling air before freezing
   Air trapped in bags can lead to freezer burn, ice crystals, and reduced milk quality.
4. Poor labeling / “lost” milk
   Without dates, you may end up using newer milk while older milk spoils.
5. Storing in the door
   The freezer door has greater temperature fluctuations. Milk stored there may degrade faster.
6. Using random containers that aren’t designed for freezing
   Lead to leaks, breakage, or nutrient loss.

How to Organize and Stack Your Freezer Stash

Good organization helps you access what you need quickly and preserves milk quality.

• Flatten and stack — flat shapes freeze more evenly and stack neatly, saving space.
• Use bins or trays — group milk by week or month; maybe use color-coded bags if helpful.
• Place newer milk in back, older in front — FIFO (first in, first out).
• Store by size / ounce — separate small portions (e.g. for short outings) vs larger ones (for longer days).
• Keep thawing milk in fridge, not countertop — until you’re ready to warm or use.

Freeze It Flat by MILKworx — What It Is & Why It Helps

Now let’s talk about Freeze It Flat (sold through Mammaway) and how it solves many of the pain points above. 

What is Freeze It Flat?

Freeze It Flat is a breastmilk storage tool that helps you freeze breastmilk bags completely flat, using recycled plastic plates plus silicone elastic straps to hold the bags in place. It can freeze one or two bags at once. 

Key features include:

• Perfectly flat freezing — no more bulky, awkwardly shaped bags.
• Up to ~30–50% space savings in freezer. 
• Silicone straps keep bags secure and flat (even if freezer or unit shifts). 
• Works with single or double bags. 
  

How Freeze It Flat Solves Common Freezer Storage Problems

ProblemHow Freeze It Flat HelpsUneven freezing / bulky bagsBy holding bags flat, milk spreads evenly and freezes uniformly.Wasted freezer spaceFlat bags stack and organize; you can store more milk in the same area.Bags getting mangled or leakingSecure placement helps prevent bag shifting, bending, damaging seals.Frustration finding oldest/most needed milkWhen bags are stacked flat and labeled, you clearly see what’s available.

How to Use Freeze It Flat

1. Pump milk and pour into a suitable breastmilk storage bag. Remove as much air as possible.
2. Seal the bag and label it (date, ounces).
3. Slide the bag into the Freeze It Flat plate(s), using the silicone elastic straps to secure it. If you have two small bags, most models allow stacking in one unit. 
4. Place the unit flat in freezer. Once fully frozen, you can stack FreezetItFlat units or remove milk bags (if needed) and stack them still flat.
5. Thawing: When it’s feeding time, thaw bag(s) in refrigerator overnight or by warm water.

Tips to Maximize Freezer Storage with Freeze It Flat

To get the most out of your freezer stash and your Freeze It Flat tool:

• Use consistent-size bags to make stacking easier.
• Freeze in small portions if you often feed small amounts, so you don’t have much leftover.
• If using chest freezer vs. upright, learn how its layout works best for flat stacking.
• Label clearly: week + date + ounces.
• Keep a small inventory (on paper or digital) to know what you have—helps avoid over-freezing or forgetting older milk.

For even more tips, tricks, and real experience from moms like you, check out these posts from the MILKworx Tips & Tricks blog: 

• How to Build a Freezer Stash of Breast Milk (Even If You’re Busy!) — great for strategies when time is tight.
• 5 Mistakes Moms Make When Storing Breast Milk (And How to Avoid Them) — learn pitfalls to avoid.
• Why Every Breastfeeding Mom Needs a Freezer Stash (Even if You Exclusively Breastfeed) — helpful mindset piece. 

Example Freezing Plan

Here’s a sample plan to help put it all together if you’re starting your freezer stash:

1. Pump twice a day (morning and evening) – yields about 4 oz each session.
2. Use 4 oz bags — easier to thaw just what you need.
3. For each bag: label, remove air, place in Freeze It Flat, freeze.
4. Once frozen, stack all flat milk bags by week in a bin or shelf.
5. Keep an ongoing inventory: maybe a list in the phone or on fridge – how many bags you have for each week.

Thawing & Using Frozen Breastmilk

Freezing is only half the story — how you thaw and use matters a lot too.

• Thaw in refrigerator overnight whenever possible.
• If you need it sooner, place sealed bag in warm water (not boiling). Gently swirl to mix separated fats.
• Once thawed, use within 24 hours if stored in fridge. Do not refreeze.
• Smell & inspect: occasionally milk can smell or look off. Discard if it appears spoiled.

Final Thoughts

Storing breastmilk in the freezer can feel daunting, but with the right tools and habits, it becomes part of your routine — more manageable, more space-efficient, and less wasteful. Freeze It Flat by MILKworx makes several of the hardest parts easier: flattening bags, stacking neatly, saving space, and protecting your milk.

If you’re ready to conquer the freezer — give Freeze It Flat a try. And meanwhile, make good use of all the wisdom in the MILKworx Tips & Tricks Blog to streamline your pumping and storage process. Because every drop matters, and with the right approach, you can keep more, waste less, and feed with confidence.