What is the difference between Greek yogurt and regular yogurt?

Greek yogurt is regular yogurt that has been strained to remove much of the liquid whey. That extra step concentrates the protein and removes water, which is why Greek yogurt is thicker, tangier, and lower in volume than the yogurt you started with.

How much Greek yogurt does a litre of milk make?

Expect roughly 40–50% of your starting yogurt volume after straining, so about 400–500g of Greek yogurt per litre of milk. The longer you strain, the thicker and lower-yield it gets. Straining is the same concentration idea used in cheese making, so the cheese yield and milk-to-cheese calculators are useful analogues for estimating output.

How long should I strain Greek yogurt?

Strain cold yogurt in the fridge: 1–2 hours for a thicker breakfast yogurt, 2–4 hours for a true Greek texture, and 6+ hours (or overnight) for a dense, spreadable labneh-style result. Always strain after the batch has fully set and chilled — straining warm yogurt removes control over the final texture.

Can I use the leftover whey?

Yes. The strained-off whey is rich in protein and can be used in smoothies, baking, soups, or as a starter boost for the next batch. Don't pour large amounts down the drain if you can avoid it — it's genuinely useful.

Why is my Greek yogurt still runny after straining?

Usually the base yogurt never set properly, or it was strained while warm. Make sure the batch has reached a firm set and is fully chilled first, then strain. If the set itself is weak, recheck your starter amount and incubation temperature before blaming the straining step.

Greek Yogurt: How It Works and How to Make It at Home — Ferment Calculator

Greek yogurt starts life as ordinary yogurt. The only thing that makes it Greek is what happens after it sets: you strain out a large portion of the liquid whey, leaving a thicker, higher-protein yogurt behind.

What Greek yogurt is and how fermentation works

You warm milk, add a live yogurt culture, and hold it in a narrow warm zone while the bacteria ferment lactose into lactic acid. That acid thickens the milk and gives yogurt its tang. Then you strain — and because Greek yogurt is just strained yogurt, a good batch depends first on a good base set.

If you nail the starter amount, temperature, and incubation time, straining simply concentrates an already-good yogurt. Get the base wrong and no amount of straining will rescue it. Size your culture with the yogurt starter calculator and sanity-check the proportions with the yogurt milk ratio calculator before you heat anything.

How to make Greek yogurt at home, step by step

1
Heat the milk Warm milk to about 82°C / 180°F to denature the proteins, which helps build a firmer set. Hold it briefly, then cool.
2
Cool to culturing temperature Let the milk drop to roughly 43°C / 110°F — warm to the touch but not hot. Too hot will kill the culture.
3
Add the starter Stir in your yogurt culture (a few tablespoons of live plain yogurt, or a measured sachet). Whisk gently so it disperses evenly.
4
Incubate Hold the mixture at 40–45°C / 104–113°F for 6–12 hours until it sets. Longer incubation means a tangier, firmer base.
5
Chill fully Refrigerate the set yogurt for several hours. Straining warm yogurt removes your control over the final texture, so chill first.
6
Strain Line a sieve with a clean cloth or coffee filter, set it over a bowl, and let the whey drip away in the fridge until the yogurt reaches the thickness you want.

Milk-to-yield ratio: what to expect

Straining is a concentration step, so your final Greek yogurt weighs noticeably less than the milk you started with. As a rough rule, plan on 400–500g of Greek yogurt per litre of milk. The longer you strain, the more whey leaves and the lower — but thicker — your yield becomes. To get the exact figure for your batch, use the Greek yogurt yield calculator — set your milk volume, fat, and straining time to see the strained yield and leftover whey.

400–500g Greek yogurt per litre of milk

40–50% of starting volume after straining

82°C milk heat for a firmer set

This is the same volume-to-yield logic that drives cheese making. If you want to model that relationship more precisely for planning batches, the cheese yield calculator and the milk-to-cheese calculator are useful analogues — the idea of “how much liquid leaves and how much solid stays” is identical.

Straining times and texture guide

Strain in the refrigerator, never at room temperature — cold straining keeps the bacteria from over-souring the batch and avoids food-safety risk over a long drip.

1–2 hours thicker than regular yogurt, still spoonable and pourable — good for breakfast bowls.

2–4 hours classic Greek yogurt texture, scoopable and creamy.

6+ hours / overnight very dense and spreadable, approaching labneh.

Save the strained whey — it’s protein-rich and works well in smoothies, baking, and soups.

Troubleshooting common Greek yogurt problems

Still runny after straining The base set was weak or you strained it warm. Confirm a firm, fully chilled set, then strain longer; if the set never firmed, revisit starter amount and incubation temperature.

Too sour Usually too long or too warm during incubation. Pull the batch as soon as it sets next time, and strain for a shorter window.

Grainy or lumpy Often from overheating the milk or using too much starter. Slow the process down and measure the culture rather than eyeballing it.

Yield feels too low That is straining working as intended — Greek yogurt is concentrated. Shorten the drip time for a higher-yield, softer result.

Try the calculator

Yogurt Starter Calculator

Get the culture-to-milk amount right so the base sets firm before you strain.

Open calculator →

Keep exploring cultured dairy

Greek yogurt is one branch of a much bigger cultured-dairy family. Start at the yogurt hub for starter sizing and milk-ratio tools, try kefir if you want a thinner, drinkable ferment with its own grain-based culture, or move into cheese when you’re ready to take straining and concentration all the way. If you like your yogurt cold, see our guide on frozen yogurt, and if you are ready to buy equipment, check our best yogurt maker picks.