How long doesKefirlast in the fridge once opened?
Why the freezer is not an option here
The USDA marks the freezer as not recommended for this item, so the answer comes from the refrigerator after opening figure: 1 day to 2 days. The source fills 2 of its fields outside the freezer here, and every one of them is printed below. It is not a warning: food held at 0 °F stays safe, so a not-recommended is a verdict on what would come out of the freezer.
Every storage figure the USDA publishes for this item
The refrigerator is the only place the USDA gives this item a storage time, as it does for 64 of the 466 foods the USDA lists.
- In the freezernot recommended
- Unopened · in the fridge1 week
- Once opened · in the fridge1 day to 2 days
Turning the range into a date
Two clocks run on this item: one from the day it went into storage and one from the day the seal broke. Both are listed below, 2 rows in all.
- Unopened · in the fridgeUse by1 week after the day you bought it
- Once opened · in the fridgeUse by1 day to 2 days after the day you opened it
Is this window about safety or about taste?
The answer at the top of this page reads 1 day to 2 days in the fridge once opened. What decides that is the food and not the shelf the source files it on: Kefir, fermented milk is an animal food, or made with one. Past it, throw it out rather than taste it: a perishable food can carry enough bacteria to make you ill while it still looks and smells fine.
Every figure assumes the food was sound when you stored it, that your refrigerator holds 40 °F or below and your freezer 0 °F or below, and that the package was handled normally.
It is past the date. Now what?
Say the calculator above puts Kefir, fermented milk past its 1 day to 2 days in the fridge once opened window, or the container sat out on the counter overnight. Throw the container out without tasting it, and count any hours it already spent out of the refrigerator as part of that window rather than on top of it.
The USDA's limit for perishable food standing at room temperature is 2 hours, or 1 hour when the kitchen is above 90 °F, and that clock runs whatever the storage figure says. The FoodKeeper entry this page is built from prints storage times and nothing else, so anything past them here is USDA and FSIS guidance rather than a figure from the source. The whole rule, including the cases the source does not cover, is set out under what to do when the date has passed.
Is that a long time?
Among the 29 items the USDA files under Dairy Products & Eggs, this item ranks 25 by how long it keeps outside the freezer. Quark, fresh cheese holds 10 days, Eggnog, commercial holds 5 days. Among the 340 foods the USDA also gives a refrigerator figure, it keeps longer than 39% of them.
Items that behave the same way
The 6 items below are the closest match to this item by storage behavior, running 4 days to 10 days and bracketing its 1 week.
Products the USDA rates in the same places
6 other products are rated in exactly these places — refrigerator from the day of purchase and refrigerator after opening — out of the 466 in the file, so this is an uncommon shape of record. The nearest of them by keeping time are Cottage cheese, Bamboo shoots and Ricotta. They are listed below with their own answers, closest first, which is why this list differs from the one on their pages. Of the 6 shown, 6 keep longer than this one. The longest-keeping of them is Horseradish at 12 months.
- Cottage cheese1 week in the fridge once openedup to 2 weeks sealed in the fridge
- Bamboo shoots5 days in the fridge once openedup to 2 weeks sealed in the fridge
- Ricotta1 week in the fridge once openedup to 2 weeks sealed in the fridge
- Caviar2 days in the fridge once openedup to 4 weeks sealed in the fridge
- Vegan Cheddar Cheese3 days in the fridge once openedup to 4 months sealed in the fridge
- Horseradish3 months in the fridge once openedup to 12 months sealed in the fridge
Closest by shape, but not an exact match — they share most of these places, not all of them.
- Egg substitutes3 days in the fridge
- Eggnog3 days sealed in the fridge
The rest of the Dairy Products & Eggs shelf
The USDA puts this product on the Dairy Products & Eggs shelf together with 28 others, and 24 of them keep longer outside the freezer. The shelf runs from Powdered milk at 5 years down to Pudding at 2 days. Nearest this product by window are Eggnog, Egg dishes and Egg substitutes, which is the order the list below is printed in. Across the whole of Dairy Products & Eggs the same product ranks 25 of 29. The middle of the shelf is Dips, at 2 weeks.
- Eggnog5 days3 days sealed in the fridge
- Egg dishes4 days3 days in the fridge
- Egg substitutes4 days3 days in the fridge
- Soy milk10 days7 days in the fridge once opened
- Almond milk10 days7 days in the fridge once opened
- Rice milk10 days7 days in the fridge once opened
- Coconut milk10 days7 days in the fridge once opened
- Quark10 days7 days in the fridge
If it has to keep longer than this
If it has to keep longer than 1 week, the Dairy Products & Eggs aisle gives 19 products that hold at least twice as long outside the freezer. The smallest step up is Buttermilk at 2 weeks against this one's 1 week; after it come Cottage cheese, Cream cheese and Dips. They are printed below in the order the step gets bigger, not alphabetically. In the other direction, 1 entry in the category keeps half as long or less, Pudding among them. The largest step the category offers is Powdered milk at 5 years.
- Buttermilk2 weeks1 week sealed in the fridge
- Cottage cheese2 weeks1 week in the fridge once opened
- Cream cheese2 weeks2 weeks sealed in the fridge
- Dips2 weeks2 weeks sealed in the fridge
- Whipped topping2 weeks2 weeks sealed in the fridge
- Yogurt2 weeks1 week sealed in the fridge
- Ricotta2 weeks1 week in the fridge once opened
- Cheese Curds2 weeks2 weeks in the fridge
The record this page is built from
This page is built from a single FoodKeeper row, record 25 — the source’s own number for it, not a position — one of the 661 rows in the snapshot. That row fills 2 of the nine storage slots with a time, and the binding figure on it is printed by the source in weeks, which is the unit this page keeps rather than converting it to days. 1 slot is marked not recommended, which is an answer rather than a gap.
Where these numbers come from
Every range on this page is published by the USDA FoodKeeper and reproduced unchanged. The multipliers, the rankings, the percentages and the dates are ours, computed from those ranges. Where the source gives a span such as 3 to 5 weeks, comparisons use the upper figure, and the full span is always printed.
Rankings cover only the items the USDA gives a usable figure for, and identical ranges share a place rather than being ordered arbitrarily. Neighbors are chosen by nearest storage time within the same category, never alphabetically: two foods filed next to each other by name usually have nothing to do with each other. The freezer is excluded from ranking because it flattens almost everything.
Where the USDA lists several kinds under one name, they share one page here and every kind keeps its own windows: the source prints them as separate rows, and a page that merged them would be inventing a figure the source never published. Comparisons and the place in the category are computed for the kind the plain name means — the shell egg for eggs, the can for tuna — which is settled name by name rather than by the order the source lists its rows in, and the page names it. Where the plain name means no single kind, the page prints no single figure at all and lists the kinds instead.
Source: USDA FoodKeeper, retrieved 1 September 2026. This site computes every comparison on this page and takes responsibility for it. Found a figure that does not match the source? Tell us on the contact page, with the page and the row — the parsing is mechanical, so a mismatch is our bug and we want it. How the whole site is built, which figures are ours and where the source can be checked is on the method page.
USDA index terms: fermented, fermented milk, Kefir, milk
KeepsUntil is an independent reference built on public USDA data. It is not affiliated with, endorsed by, or connected to the U.S. Department of Agriculture or the Food and Drug Administration. Whether a given window is a safety limit or a quality window is stated on the page that prints it.