Let’s make Kefir

Milk & water kefir calculator

The kefir calculator
for a better batch.

Choose milk or water kefir, then enter the batch size you want or the grains you have. We’ll calculate your ingredients and give you a practical method.

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

The kefir calculator

Calculate your
kefir ratio.

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.

How the calculator works

A starting ratio
for your jar.

The milk kefir calculator works out grains and milk. The water kefir calculator works out grains, sugar and dechlorinated water. Both can calculate from your desired amount or the weight of grains you already have.

Kefir grains are living cultures, so use the result as a practical starting point. Temperature and culture strength change fermentation speed; taste and observe each batch, then adjust one variable at a time.

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.