Why did my bread not rise?

The six things that stop bread rising, how to tell which one it was, and whether the dough can still be saved.

Difficulty: beginner
Time: 15 min
Read: 2 min

Short answer

The usual causes are dead yeast, liquid hot enough to kill it, salt added directly onto the yeast, a cold room, or not enough time. Test yeast in warm water with a pinch of sugar before using it — if it does not foam within ten minutes, it is dead.

Yeast is a living organism with a narrow comfort zone. It needs warmth, moisture and food, and it is killed by heat above about 50°C and inhibited by direct contact with salt. Most failed loaves come down to one of those conditions being wrong rather than to technique.

What you'll need

Yeast
Thermometer or a sense of blood temperature
Bowl (optional)

Step by step

Check whether the yeast was alive before blaming anything else.Mix a teaspoon of yeast with a little warm water and a pinch of sugar. Foam within ten minutes means it is fine. No foam means it was dead.
Check the temperature of the liquid you used.It should feel just warm, around 35-40°C. Anything above roughly 50°C kills yeast outright, and hot tap water can exceed that.
Check whether salt touched the yeast directly.Salt draws water out of yeast cells and kills them on contact. Add salt to the flour on one side of the bowl and yeast on the other.
Consider the room temperature.Below about 18°C dough rises very slowly. It is not dead — it just needs several more hours, or a warmer spot.
Give it more time before giving up.Recipe timings assume a warm kitchen. Judge by size, not by the clock: it should roughly double and hold a dent when poked.
Check the flour if the dough rose but collapsed.Low-protein plain flour cannot hold gas structure the way strong bread flour can. It will rise and then sink.
Try to rescue it by kneading in fresh activated yeast.Dissolve fresh yeast in a little warm water, work it through the dough thoroughly, and prove again. This works more often than people expect.

Tips

A cold, slow overnight rise in the fridge produces better flavour than a fast warm one. Slow is not a problem.
Yeast has an expiry date and loses potency once opened. Store opened dried yeast sealed in the fridge or freezer.
An oven with only the light on, or a bowl of just-boiled water on the shelf below, makes a good proving box in a cold kitchen.

Common mistakes

Using hot water to speed things up — Above about 50°C the yeast dies instantly, and the dough will then never rise no matter how long you wait.
Mixing salt straight into the yeast — Direct contact kills yeast. Keep them apart until the flour is between them.
Judging the rise by the clock — Kitchen temperature changes proving time enormously. Judge by size and by the dent test.

Questions people ask

Can I save dough that has not risen?

Often yes. Activate fresh yeast in a little warm water, knead it thoroughly through the dough, and prove again somewhere warm. If the dough was simply cold, just giving it more time is enough.

How do I know if my yeast is still good?

Mix a teaspoon with warm water and a pinch of sugar. If it foams and smells bready within ten minutes it is alive. No activity means it is dead and the dough will not rise.