Let’s make Kefir

Milk & water kefir calculator

Good kefir starts
with a good ratio.

Tell us what you’re making and what you have. We’ll work out the ingredients and give you a practical method for your jar.

Make a batch
Milk kefir fermenting in a linen-covered glass jar beside a bottle

The kefir calculator

What’s going
in your jar?

1. What are you making?
2. What do you know?
3. Choose a ratio

Percentages are wet grain weight relative to liquid. Your culture and room will vary.

The method

Four simple steps.
One lively drink.

  1. 01

    Start clean

    Wash hands and use a clean glass jar, strainer and utensils. Use pasteurised milk or safe drinking water.

  2. 02

    Combine

    Add grains to milk and cover loosely.

  3. 03

    Let it culture

    Keep at 20–25°C, out of direct sun. Look for a clean tangy aroma and gradual acidification.

  4. 04

    Strain & chill

    Strain out the grains for your next batch. Refrigerate promptly in a clean sealed bottle.

Know your culture

Not a formula.
A relationship.

Kefir grains are living communities of bacteria and yeasts. Their speed changes with temperature, ratio, substrate and culture history.

Start with the calculator, then tune one variable at a time. Shorten the ferment if it separates or turns sharply sour; lengthen it if it stays sweet and inactive.

Before you ferment

Home fermentation is not risk-free. Discard batches with mould, rotten or putrid odours, unusual colours, or a damaged container. People who are pregnant, elderly, very young, or immunocompromised should seek qualified advice before consuming home-fermented food. Water kefir can retain sugar, contain alcohol and build pressure—especially after bottling with juice or fruit—so treat it as unsuitable for anyone avoiding alcohol unless you have verified the batch.