5 Signs Your Kefir Is Ready To Drink

With kefir it can sometimes be difficult to tell when it’s actually done and read to drink. The first few times I fermented my own I let it sit for way too long and ended up with a runny sour liquid. So, when is kefir ready to drink?

Kefir is ready to drink when the kefir grains have floated to the top and a fragmented texture becomes visible in the top half of the vessel. Sometimes the whey and the milk curds will also already have separated.

In this post, I’ve compiled my top 5 tips for making that you your kefir is ready and delicious. At first we’ll look at how long kefir should ideally ferment and what conditions affect fermentation time. In the second half of this article I’ll cover what signs to look for to make sure your kefir is done!

How long should kefir ferment?

Kefir should generally ferment between 18-24 hours. However, there are several factors that influence the time that is needed to ferment kefir such as the room and milk temperature.

First of all, let me point out that how long you ferment kefir is also a matter of personal choice. Some prefer their kefir milder and runnier and others (like me) prefer kefir a bit more sour and creamier.

That said, fermenting your kefir anywhere between 18-24 hours at room temperature should produce a fine result.

Let’s look at some factors that have an impact on fermentation time:

  • Room Temperature: The temperature in your fermentation room will have the single biggest impact on the time it takes for the bacteria to digest the lactose in milk. Generally, the warmer it is the faster this process goes. Ideally, you’ll want to keep room temperature somewhere around 21°C / 74°F.
  • Milk Temperature: Another factor that can affect fermentation time is the temperature of the milk when you add it to the kefir grains. Milk that is too cold or straight out of the fridge can cool down the grains significantly and cause them to ‘hibernate’ for a short while extending the fermentation time. To avoid this take the amount of milk you are planning on using out of the fridge a few hours before.
  • Kefir Grains to Milk Ratio: The third most impactful factor on the time it takes until kefir is done is the ratio of kefir grains to milk. When there are a lot of lactic acid-producing bacteria present in the vessel it will take much shorter for the lactose to be turned into lactic acid. Use about a teaspoon (don’t use a metal spoon) of kefir grains for half a liter or 1/4 gallon of milk.

How to tell when kefir is done?

You can generally tell by looking at the fermented milk whether it is done or not. In some cases you may also rely just on the time that has passed since fermentation started and on a consistent room temperature.

Kefir Fermentation Time

If all else fails, simply take out a small amount of kefir and try it. If it taste slightly sour and has the consistency of buttermilk it is ready to be consumed.

  • Visual Cues: The easiest way to tell when kefir is ready is to examine the fermentation jar. This is why it is also beneficial to use a transparent glass jar for milk fermentation. Then, you’ll be able to tell when the kefir grains float to the top or the whey and the curds have separated. I’ll go into more detail regarding each of these signs in the next section.
  • Consistent Time/Temperature: If you cannot spot any visible signs by just looking at the fermentation jar you might also be able to tell when kefir is ready based on the time that has passed and the room temperature. However, this method is less reliable as external variables might change that affect how long your kefir takes to ferment.
  • Smelling & Tasting: Using our olfactory senses is definitely the most pragmatic and trustworthy way to make sure the kefir is just right. The disadvantage is that you will have to disturb the live cultures in their digestive process when tasting. It’s a bit like cutting open a steak to check if it’s ready. There are better ways!

So, without any more ado, let’s look at the 5 sign that your kefir is ready to drink.

5 signs your kefir is ready to drink

The most reliable sign that your kefir is ready are floating grains, a soil horizon-like texture, separation of whey and curds, the smell and the taste.

Floating Grains

Kefir Grains Floating

At around 6-12 hours of fermentation, you will see that your kefir grains have moved to the top of the jar and are now floating on the milk. This does not always occur at the same exact time but also depends on the milk-kefir grains-ratio.

Although your kefir will still be in its early stages of fermentation it is ready to drink! The taste will be much less sour and fully fermented kefir and the consistency will be thinner as well.


Kefir Texture

Somewhere between 12-18 hours, you will likely see a texture form in the top half of the fermentation vessel. This actually is the start of the separation of whey and milk curds. Most of the lactose has been broken down into lactic acid at this point and your kefir is ready to drink.

At this point you may always have to stir the mixture lightly with a wooden spoon in order to strain the now thicker liquid. The taste will still be fairly mild, however, this perfect if you plan on doing a second fermentation and don’t want overly sour kefir.


Kefir Separation of Whey and Curds

The whey and curds separation starts to occur after around 18-24 hours. Sometimes it may happen even faster at higher room temperatures. The kefir batch above has actually been fermented for around 36 hours. But since it was winter time and my average room temperature dropped by about 5°C the entire process just took longer 🙂

This is generally what I like my kefir to look like if I don’t plan on second fermenting it. This will product a slightly sour taste that is just to my liking. I recommend you experiment with trying your kefir at different stages to see which you like best!


Smell When Kefir Is Done

Another sign that kefir is done is the smell the yeast exudes when it accumulates at the top of the fermented milk. It will be a tart, tangy, sour smell that can easily resemble the smell of spoiled milk.

The advantage of this over actually tasting the kefir is that you can simply remove the paper towel cover and stick your nose in the jar without stirring the liquid and disturbing the working bacteria.


Kefir Taste Test

And lastly, of course, tasting the kefir is the ultimate sign to tell when it’s ready to drink. The taste that you’re looking for is a slightly sour taste – sort of like sour milk – with the consistency of buttermilk.

Once you have tasted a small amount you can also just cover the jar again and let the bacteria continue their work for a few more hour if the taste was not yet to your liking.

Sooner or later you’ll have the perfect kefir formula down to its details and tasting probably won’t be necessary anymore.


Making sure your kefir is ready to drink is a simple process. There are several signs that you can look for. The easiest is to watch the fermentation jar carefully and notice when the grains float to the top and the whey starts to separate from the milk curds.

Another way is just to use your senses and smell or taste the fermented milk. Everybody likes their kefir a bit differently which makes fermentation such a personal experience.

Experiment with different times and textures to see which one you like best. After all, you’re the one drinking it no matter what the ‘standard procedure’ says.


  • Hi, I'm Marvin! In early 2019 I started fermenting sauerkraut, kefir, and kombucha and noticed the incredible health benefits that came with it. I was less irritated, had fewer allergies and my skin got better. I started this blog to share how fermented foods have helped me and how simple they are to prepare! Look around and see what speaks to you and all the best on your fermentation journey!

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