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Can you freeze breast milk in bottles?

Aligned with CDC guidance; not medical advice · Updated July 2026

Quick answer: Yes. Use plastic bottles rated for freezing or freezer-safe glass, fill only three-quarters full to leave expansion room, and label the date. Standard thin glass bottles can crack as milk expands, and bottles cost you significant freezer space versus flat bags.

The expansion rule is not optional

Milk expands roughly 10 percent when it freezes. A bottle filled to the neck will force its lid or crack its walls, and you will find out during the thaw. Three-quarters full, always, and lids on loosely until frozen if the manufacturer suggests it.

When bottles beat bags in the freezer

Short-term freezing of a week or two, milk destined for daycare in the same container, and households that reuse rather than buy bags. For deep stashes, flat bags still win on space several times over: a drawer that holds 15 bottles holds 60 filed bags.

Milk First's expiring view flagging bags that need attention

In Milk First

Every bag and bottle you add gets its best-by and use-by dates computed automatically from these exact rules, the oldest safe milk sits on top of the Use next queue, and a warning arrives the day before anything expires, while you can still act.

Set up expiry reminders · How the Use next queue works

Milk First keeps every date, clock, and rule from this page automatic, so 3 AM you never has to remember any of it.

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