What does it cost to make kefir at home?

Why every litre costs less than the last

Because you never drink the culture. You strain the grains out, put them back into fresh sugar water, and the next day they start again.

You pay for the grains once and that cost is shared across every litre you make with them. One batch a day comes to 30 litres after a month, about 182 after six months and 365 after a year. The longer you keep your grains going, the smaller their share of each glass.

And they grow: with 60 g you make 2 litres a day without buying anything more. To keep them lively, holidays included, follow Caring for water kefir grains.

The grains' share of a litre of water kefir

The sum is simple: what you paid for the grains divided by the number of litres. Here are the rough figures with 30 g and one litre a day, rounded.

With the 60 g pack you make 2 litres a day from the start, so 730 litres over a year. From the second year on, the culture hardly counts at all: only the ingredients are left.

The ingredients in a litre of water kefir

Four tablespoons of sugar (about 60 g), a dried fig, a slice of lemon and a litre of water. The amounts below are cautious estimates based on ordinary UK supermarket prices; depending on the brand, the shop and the pack size you will be a little over or under.

The fig is usually the biggest item. A large bag works out cheaper than a small one, as long as you keep it well sealed in the cupboard. Everything about choosing water and sugar is in Water and sugar for water kefir, and the step-by-step method is in How to make water kefir.

And a litre of milk kefir?

Here the whole milk is the main cost. The grains fade into the background over time, exactly as with water kefir.

The basic recipe is 20 g of milk kefir grains in 1 litre of whole milk, 24 hours at 20 to 25°C. With 10 g you make half a litre a day, and within a few weeks the grains grow enough to move up to a litre. The grains start at £14 for 10 g. In the supermarket, a 4-pint bottle of whole milk (the blue top, 2.272 litres) costs roughly one pound fifty to one pound seventy, so 65p to 75p a litre.

So a litre of milk kefir costs barely more than the milk itself, well under the price of a carton of buttermilk for your scones. Whole, semi-skimmed, Channel Island or goat's milk: the differences in taste and texture are in The best milk for kefir.

Homemade kombucha: a different sum

With kombucha too, you pay for the culture once. The rhythm is different, though: fewer litres a week, and there is tea in the mix.

For 1 litre you need 1 SCOBY with 1 cup of starter liquid (about 250 ml), 80 g of sugar and 3 tea bags, or about 8 g of loose tea. The jar works for 7 to 10 days. With a single one-litre jar you make about three batches a month, around 36 over the year. The SCOBY with its starter liquid is £16.

If you get through a box of everyday breakfast tea every few weeks anyway, three bags per litre will barely register: a proper brew for the SCOBY costs less than your morning cuppa. With every batch the SCOBY forms a new layer, and that layer can start a second jar: you double the litres and halve the culture's share in one go. Ordinary tea works very well; the teas that suit it best are in The best tea for kombucha, and the full method is in How to make kombucha.

And a litre of ginger beer?

The ginger beer plant (£14) works like water kefir grains: you strain it, feed it and it carries on growing. The basic recipe is 20 g of plant, 1 litre of water, 60 g of sugar, 2 slices of fresh ginger and 1 dried fig, 24 to 48 hours in the jar, then 48 hours in a closed bottle. A new jar every two days or so gives about 180 litres a year, so the plant comes to around 8p a litre over twelve months. With the sugar, ginger and fig, a litre of homemade ginger beer lands at roughly 30p to 40p, with a properly spicy fizz you choose yourself. The method is in How to make ginger beer.

Compared with the bottles in the shop

Tesco, Sainsbury's, Waitrose and the rest all stock ready-to-drink kefir and kombucha now, usually in small bottles, and once you work it out per litre the price runs into pounds rather than pence. At home you only pay for the ingredients, and you choose the sugar, the fruit and how sharp it gets. A single shop bottle often costs more than a whole week of homemade kefir.

The other costs to plan for

Not much, and only once: a glass jar, a plastic or stainless steel sieve, a tea towel, an elastic band and a few swing-top bottles. No electricity either.

The one expense worth avoiding is starting from scratch because you forgot your grains. A proper break in the fridge sorts that out, and the most common slips are in Kefir: the 10 most common beginner mistakes.

Delivery is the last item. Standard tracked delivery in the UK is £4.90, and free from £35; spread over a year of daily batches it comes to about a penny a litre. Express tracked delivery is £14.90. All prices include VAT. To start several drinks at once, the fermentation starter kit, with water kefir, milk kefir and kombucha, saves you £7 compared with buying each one separately, and on its own it passes £35, so delivery costs nothing. You can pay by Visa or Mastercard debit or credit card, PayPal, Apple Pay, Google Pay or Klarna (Pay in 3). All the details are on Delivery and payment.

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