Find more advice on perfecting this fermentation method along with kefir recipe recommendations in our guide on how to make kefir.


  • ½ tsp kefir grains (see tip, below)
  • 1 pint milk (organic whole milk for best results)
  • 1 slice lemon or 1 drop lemon oil (optional)

You will also need

  • 500ml clip-top jar with gasket for fermenting (or jar, cover and rubber band)
  • a sieve, jug/bowl, storage bottle or a straining funnel and wide-necked bottle


  • STEP 1

    Put ½ tsp kefir grains in the jar. Add the milk, leaving about 2cm head room if using a clip top jar, or at least 5cm for a cloth-covered jar.

  • STEP 2

    Set aside at room temperature for 18-24 hrs to ferment. It’s turned to kefir when the milk has thickened. It may have set and separated, with pockets of whey forming – this is quite normal.

  • STEP 3

    If you can’t strain it straight away, put it in the fridge to stop it fermenting further, the flavour can get quite strong – you can strain it anytime over the next 48 hrs.

  • STEP 4

    Strain the kefir through the sieve or straining funnel into the jug or bottle. The grains are quite robust and will withstand gentle stirring.

  • STEP 5

    You can drink it straight away, flavour and refrigerate it (a slice of lemon peel or a drop of lemon oil add a delicious fresh taste), or leave it at room temperature for a few hours to make it taste stronger. Storing it in the fridge will slow down the fermentation by the microbes and it should remain pleasantly useable for 7-10 days.

  • STEP 6

    In order to make some more kefir, rinse out the jar, return the grains (don’t wash them, there’s no need), and start again from the beginning.

What is kefir?

Kefir is a tangy fermented milk similar to yogurt that's packed with beneficial probiotic bacteria (up to 30 different species of probiotic bacteria and yeasts). It’s been an essential part of the diet in Eastern Europe for the last 2000 years, and gradually has made its way to the UK. A rich source of bioactive peptides, vitamins, minerals and enzymes, it’s been studied by scientists for over a hundred years. It's produced using kefir ‘grains’. These 'grains' are actually bacteria and yeast that look like tiny cauliflower florets, bound together in a kefiran polysaccharide matrix. You use the grains to ferment milk, then strain them out to use again.

What equipment do I need to make kefir?

Making kefir is very easy and you’ll generally have what you need in your kitchen already. There are two systems (see below), and, depending on which you choose, you’ll need slightly different jar. You’ll also need a spoon, sieve and jug or straining funnel, and a wide-necked storage bottle.

What’s the best way to make kefir?

For a stronger flavour, use an open system: cover a 500ml jar with a cloth cap or kitchen towel and rubber band, ensuring there are several inches of air above the milk. The closed system uses a 500ml clip-top jar with a rubber gasket to keep oxygen out. The microbes in the kefir grains are able to grow well with just a little oxygen present. These conditions will also ensure that Lactobacilli grows better than other types of microbes, reducing yeasty flavours and fizz (though the amount of grains used is also very important – the more grains you use, the faster the fermentation and stronger the flavour. Use 5-10g grains per litre of milk for a milder flavour).

Where can I buy kefir grains?

If you know someone who already makes kefir, ask them if you can have some. As little as half a teaspoon will be enough to make your own. Alternatively, fresh grains can be purchased online. If they arrive in the post, they may need a little reinvigorating after their journey – put them in a small jar and cover with whole milk (you won’t need more than 100ml). Cover and leave at room temperature for 12-48 hours until the milk has set (it varies depending on the milk used and its temperature). When it does, you’re good to go and can scale up.

Which milk should I use to make kefir?

Cow's milk

  • Use whole organic milk if you can. This is easier to work with when you first start, as skimmed sets more softly. Organic milk has superior nutritional quality, but make sure it's very fresh, as older milk can result in an odd flavour.
  • Any fresh animal milk works, from skimmed and full-fat Jersey, to goat, cow or even UHT. The higher the milk’s fat content, the thicker the kefir.
  • You can use homogenised or unhomogenised milk, but it’s worth noting that with high fat varieties of unhomogenised milk, sometimes the grains get stuck in the cream and the milk won’t set – you’ll need to stir or shake it a few times while it’s fermenting.

Dairy-free milks

  • You can also make kefir with plant-based alternatives like coconut, soya or oat milk. Whichever you choose, it needs a high-calorie content and about 3.5g sugar per 100ml, as this will be the microbe’s source of carbohydrate.
  • Soya milk makes excellent, thick kefir, and the grains usually grow in this medium. Canned coconut cream is a better choice than coconut milk and creates a thick, tangy, almost yogurt-like consistency. Choose an organic brand as these have no additives.
  • How well they will survive a non-dairy lifestyle entirely depends on your own kefir grains and the microbes they contain. If you notice that they are not making kefir or growing much, try refreshing them in some dairy milk for a few days.
  • With the exception of soya milk, which contains many short-chain peptides, health benefits of other milk alternatives have not yet been investigated.

How do I know when the kefir is ready?

The grain-to-milk ratio and temperature both affect how quickly milk will become kefir. Put the jar somewhere (out of direct sunlight) where you can keep an eye on it. Try to catch it when just set for a milder flavour. If it separates into curds and whey, don’t worry, as it can be easily mixed back together. With practice, you’ll be able to time it just right. It’s harder to tell with skimmed milk, which gives a much softer set. Poke with a spoon if you aren’t sure if it’s thickened and smell it – if it smells slightly yogurty or mildly cheesy, it’s done.

At first, it might take up to 48 hours for the milk to thicken. You can tell it’s ready as the milk will set just like yogurt. Pockets of whey might appear – don’t worry, this is normal and they will mix in during straining.

Is kefir good for you?

Kefir is a great source of protein, calcium and probiotics. Probiotics are known as ‘friendly bacteria’ and may ease IBS symptoms such as bloating and digestive distress in some people. Enjoying kefir regularly has also been associated with benefits for blood pressure, cholesterol balance and blood sugar management.

Read more about the health benefits of kefir in our expert health guide.

How should kefir be stored and how long does it keep?

Once strained, keep kefir in the fridge. This will slow down the fermentation by the microbes. It should remain pleasantly useable for seven to 10 days. It will not ‘go off’ as such, as it's already fermented, but the flavour might become rather strong. You can make a larger batch once a week if you don’t want to make it daily. Half a teaspoon of grains will even convert a much larger volume of milk to kefir – add a little kefir in with the grains to get things started more quickly if you’re scaling up.

How should kefir grains be stored?

In between batches, keep the grains covered in a little jar of milk on the worktop for up to a week or up to three weeks in the fridge. Change the milk if you’re still not using them or they will starve. Kefir grains are living organisms and will gradually grow (not in all milk alternatives, though). When they’ve doubled in size, which might take two or three weeks with daily making, take out half of them and give them to a friend or freeze them. If you don’t remove the excess, you will notice the flavour of the kefir changing.

How much kefir should I drink?

You will be introducing many new species to your gut, which can occasionally result in mild stomach upset symptoms, so the best advice is to start gradually with a couple of teaspoons for the first day or two, doubling up over the next few days to about 150ml (though this is arbitrary – you can’t overdose as such).

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