Power went out? A bag-by-bag triage for your freezer stash

First: don't open the freezer door. A full freezer that stays closed holds its temperature about 48 hours; a half-full one about 24 hours, per the CDC's infant feeding in emergencies guidance. Most outages end long before that, and most of your stash comes through untouched. This page is for the hours in between — and for the bags that didn't make it.

How long does frozen breast milk last without power?

These are estimates for an unopened appliance, from the CDC's emergencies toolkit and FoodSafety.gov's USDA guidance (both checked 2026-09-03):

Two things decide which row you're in: how full the freezer was, and whether the door stayed shut. A packed freezer is its own insulation — every frozen bag helps keep the others frozen. The moment the door opens, the closed-freezer estimate stops applying and the ice crystals in each bag become the only thing you can go by.

Can I refreeze breast milk that started to thaw?

Per the CDC's emergencies guidance: milk that still contains ice crystals is still considered frozen, and it can be refrozen. Milk that has fully thawed — completely liquid, no crystals — cannot be refrozen. That's the same "never refreeze thawed milk" rule from the everyday storage table, applied to a freezer that lost power.

One honest note about the app: Milkloft is deliberately stricter than this. Inside the app, a bag that has left the freezer is never put back, even while it's still solid, because a phone can't see whether there's ice left and the failure mode of guessing wrong is refrozen thawed milk. Where the app's rule is tighter than the CDC's, it says it's the app's rule — not the CDC's. On this page, the CDC's ice-crystal rule is the rule.

What do I do with the bags that fully thawed?

Treat them like any thawed bag: per the CDC, use within 24 hours in the refrigerator, counted from when the milk finished thawing — and if you don't know when that was, count from the moment the power went out. That's the cautious reading, and it's what the tool below does. Once warmed or brought to room temperature, the window is use within 2 hours (CDC).

If the power is still out, the fridge is only an estimated 4-hour refuge when unopened (CDC). An insulated cooler packed with frozen ice packs is the CDC's travel row — up to 24 hours — and it's a reasonable place to hold thawed bags you plan to use that day. A few of those bags become today's bottles; the rest get used tomorrow or discarded at the 24-hour mark. Nothing thawed goes back into the freezer.

Which bags can I keep? Run the triage

Set the state to "power outage", enter when it went out, how full the freezer is, whether the door opened, and what the ice crystals look like. The verdict cites the row that decided it.

How do I triage the freezer bag by bag?

1. Keep the door closed. Do not open the freezer to check. A full freezer holds its temperature about 48 hours with the door closed, a half-full one about 24 hours (CDC).
2. Count the hours. Note when the power went out and how full the freezer is. Inside the estimated window, the milk is still frozen — leave it alone.
3. Check for ice crystals. Once the window has passed or the power is back, open the freezer and look at each bag. Ice crystals still visible means it still counts as frozen (CDC).
4. Sort the bags. Keep the frozen ones in the freezer. Move fully thawed bags to the refrigerator — they are on a 24-hour clock from thawed and cannot be refrozen.
5. Decide bag by bag. Use the thawed bags first, within 24 hours in the fridge. Discard anything thawed beyond that window, and anything you cannot place on the timeline.

The bags you can't place on the timeline — no date, no idea when they went in, no idea when they thawed — are the ones that hurt, because the rules can't help you with them. That's an argument for labeling every bag before the next storm, not for keeping them.

How do I prepare for the next outage?

• Keep the freezer full. Per the CDC, a full freezer holds about twice as long as a half-full one. Jugs of water in the empty spaces do the same job as milk.
• Know what's in there — how many bags, which is oldest, which were already thawing in the fridge. In an outage the thawing ones are the first to sort.
• Date every bag, so "how long has this been thawed" has an answer.
• Agree on the door rule with everyone in the house before it matters. Nobody opens the freezer "just to check".

These are estimates from published guidance, not medical rules. When a specific bag is a judgment call — an unknown thaw time, a freezer that was opened more than once — ask your pediatrician or an IBCLC rather than guessing.

Milkloft's power-outage triage is built into the free app: tell it when the power went out and whether the freezer was full, and it sorts your real inventory into "still frozen", "use soon" and "discard" — bag by bag, with the source shown beside the verdict. Every date is an estimate from guidelines you can read and edit.