Yogurt Making Calculator

A starter amount of 1–3% of your total milk volume is the standard recommendation. Using 2% (20 ml per litre) gives a reliable set without over-acidifying the batch. Using more than 3–4% can cause the yogurt to become too sour or grainy, as the bacteria compete for lactose too quickly.

Most yogurt cultures thrive at 40–46°C (104–115°F). A standard setting of 43°C produces a firm, mildly tangy yogurt in 6–8 hours. Lower temperatures (38–40°C) give a milder flavour but require longer incubation of 8–12 hours, while higher temperatures speed setting but can produce a sharper taste.

Heating milk to around 82–85°C (180°F) denatures the whey proteins, which improves the yogurt's texture and helps it set firmer. It also kills any competing bacteria that could interfere with your starter culture. The milk must then be cooled to your incubation temperature before you add the starter, as high heat will kill the live cultures.

Incubation time typically ranges from 4 to 12 hours depending on temperature, starter percentage, and your preferred tanginess. At 43°C with 2% starter, expect 6–8 hours for a standard set. Leaving it longer produces a more sour flavour. Once the yogurt has set to your liking, refrigerate it immediately to stop fermentation.

The most common methods are: adding 3–5% skimmed milk powder to the milk before heating, straining the finished yogurt through a muslin cloth to remove whey (making Greek-style yogurt), or using a higher-protein milk like whole milk or goat's milk. UHT milk also tends to produce a slightly thicker result without any additions.

You can use whole, semi-skimmed, or skimmed dairy milk — whole milk gives the creamiest result. Goat's milk yogurt is naturally thinner but has a distinctive flavour. Non-dairy milks like oat, soy, and coconut can work but require a vegan starter culture and may need added thickeners like agar or tapioca starch, as they contain less protein to help the yogurt set.

Yes — plain live yogurt from the supermarket works as a starter, provided it contains active live cultures (check the label for 'live bacteria' or 'Lactobacillus bulgaricus' and 'Streptococcus thermophilus'). Use it at 2% of your milk volume. Each batch you make can then be used as the starter for the next, though the culture weakens after 5–10 generations and you may need fresh starter.

You should expect a yield of roughly 90–95% of your original milk volume, as a small amount of whey may separate or be lost. For example, 1 litre of milk typically produces around 900–950 ml of finished yogurt. If you strain it into Greek-style yogurt, the yield drops to around 50–60% by volume but the protein content per gram increases significantly.