What You Need

  • 1 litre whole milk (full-fat gives the creamiest result; skim milk produces thinner yogurt)
  • 2 tablespoons plain yogurt with live active cultures (this is your starter — check the label for "live cultures" or "active cultures")
  • A thermometer (essential for this recipe)
  • A clean jar or bowl with a lid
  • A warm place to incubate (oven with just the light on, yogurt maker, or a warm water bath)
  1. 1

    Heat milk to 85°C

    Pour milk into a heavy saucepan. Heat over medium heat, stirring occasionally, until it reaches 85°C. This kills unwanted bacteria and denatures the proteins — it is what makes the yogurt set thickly. Do not boil. Use a thermometer.

  2. 2

    Cool to 43°C

    Remove from heat and let the milk cool to 43°C — the ideal temperature for yogurt bacteria (Lactobacillus). Above 50°C kills the cultures; below 35°C they are too inactive. Stir occasionally to speed cooling. Place the pot in a bowl of cold water to speed this up.

  3. 3

    Stir in the yogurt starter

    Take 2 tablespoons of warm milk from the pot and mix with your 2 tablespoons of plain yogurt in a small bowl until smooth. Pour this mixture back into the main pot and stir gently to distribute the cultures evenly throughout.

  4. 4

    Pour into jars and keep warm for 6–8 hours

    Pour into clean jars or a bowl. Keep at 40–45°C undisturbed for 6–8 hours. Options: place in an oven with just the light on (light generates enough warmth), use a yogurt maker, wrap in towels and place in a warm spot, or use a warm water bath. The longer it incubates, the tangier and firmer it gets.

  5. 5

    Refrigerate for at least 4 hours

    Do not disturb during incubation — movement prevents setting. After incubation the yogurt will look set but is still quite soft. Refrigerate for at least 4 hours (or overnight) — it firms up significantly in the fridge.

For Greek yogurtAfter incubation, line a colander with muslin or cheesecloth, pour in the yogurt, and leave in the fridge for 2–4 hours to drain. The liquid (whey) drips away leaving thick, creamy Greek-style yogurt. Save the whey for smoothies or baking.
Save some as starterKeep 2 tablespoons of your homemade yogurt to use as the starter for your next batch. You can keep reusing it indefinitely — homemade yogurt cultures stay active for weeks in the fridge.

Frequently Asked Questions

Most common causes: milk was too hot when you added the starter (killed the cultures), too cool and the bacteria were inactive, or the incubation environment was too cold. Also check your store-bought yogurt starter actually has live active cultures — some heavily processed yogurts do not. If it did not set, try again with a fresh starter and be precise with temperatures.
Up to 2 weeks in the fridge in a sealed container. It gets tangier over time as the cultures continue to produce lactic acid (slowly, in the cold). Signs of spoilage: pink or green mould, very strong off-smell. The normal yogurt smell is tangy but clean.