Fermentationist
Tools / Starter dose calculator

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Starter dose calculator

How much yogurt, culture or kefir grains to add for your volume of milk. Works in this browser; nothing is sent anywhere.

Your batch
Your starter

Extension guides use 2 tablespoons per quart, about 3% of the milk 1, up to ¼ cup per quart, about 6% 2. The percentages are our conversion.

Use the amount on the label for its volume of milk; home yogurt packets are usually one 5 g packet per quart 2. Culture makers set doses per volume of milk 3.

Research uses 20–50 g of grains per litre 4; Colorado State’s home method uses 2 tablespoons per 2 cups of milk 5.

You need

1 litre of milk at 3% needs 30 ml of starter.

Record this batch

How the numbers are worked out

  • Yogurt as starter: millilitres of starter = litres of milk × 1000 × percentage ÷ 100. A tablespoon is counted as 15 ml. Extension guides range from about 3% 1 to about 6% 2
  • Use homemade yogurt as starter within 5–7 days of making it 1
  • Freeze-dried culture: the label amount is scaled in proportion to your volume. If you cannot measure part of a sachet accurately, use the whole sachet for the volume it is made for
  • Kefir grains: grams of grains = grams per litre × litres. More grains, a longer time or a warmer room give a tangier kefir 56

The calculator scales amounts; it does not decide whether a culture is suitable or a batch is safe. Follow the instructions on your culture pack when they differ.

Sources

  1. University of Illinois Extension: Making yogurt at homeHeat milk to 82–85 °C (180–185 °F); cool to 42–46 °C (108–115 °F); 2 tablespoons of yogurt per quart of milk; incubate 6–10 hours; ready when lightly gelled like thin pudding; refrigerate at or below 4 °C (40 °F) and eat within 14 days; use homemade yogurt as starter within 5–7 days; strain 2–4 hours for Greek-style and 8–24 hours for yogurt cheese, covered in the refrigerator; troubleshooting table. Accessed 2026-10-09.
  2. University of Alaska Fairbanks Cooperative Extension: Making yogurt at home (FNH-00062)Heat to 85–93 °C (185–200 °F) for 10–20 minutes, do not boil; culture is killed above 54 °C (130 °F) and grows poorly below 37 °C (98 °F); adding culture to milk over 46 °C (115 °F) can kill it; incubate 4–7 hours at 43 °C (110 °F); sets at pH 4.6; one 5 g freeze-dried packet or ¼ cup yogurt per quart; discard batches that fail to set or show microbial growth or odd odours; keeps about 10–21 days at 4 °C. Accessed 2026-10-09.
  3. Danisco CHOOZIT MA 4001 product descriptionA mesophilic culture maker gives 2.5–5 DCU per 100 litres of milk for quark: culture doses are set by the maker per volume of milk. Accessed 2026-10-09.
  4. Garrote et al. (1998), Characteristics of kefir prepared with different grain:milk ratios, Journal of Dairy ResearchTraditional kefir is fermented at 20–25 °C for about 24 hours; studies use 20–50 g of grains per litre; there are no rules for household kefir. Accessed 2026-10-09.
  5. Colorado State University Extension: Understanding and making kefir2 tablespoons of grains per 2 cups of pasteurised, not ultra-pasteurised or UHT, milk; 18–29 °C (65–85 °F) in the dark for 18–24 hours; ready when slightly thickened with an acidic aroma, pH 4.0–4.5; strain with plastic, nylon or stainless steel; a shorter time or more milk fixes a watery whey layer. Accessed 2026-10-09.
  6. Tetra Pak Dairy Processing Handbook: Fermented milk productsIndustrial yogurt milk is heated to 90–95 °C for about 5 minutes; incubation 4–5 hours at 42–43 °C to pH 4.2–4.5; concentrated yogurts including strained yogurt and skyr lose whey after fermentation; raising protein too high before fermentation risks sandiness; kefir is made with 1:20–1:30 grains to milk at about 23 °C for about 20 hours; temperature controls the acid, alcohol and carbon dioxide in kefir. Accessed 2026-10-09.

Numbers on this page come from these sources. Where sources give a range, we quote the range rather than a single figure.