Pizza dough didn't rise

What you're seeing

Four hours in and the ball is the size it was when you put it away. No dome, no bubbles pressed against the side of the container, no lift when you tilt it. Press a finger in and the dent just stays there — there is no gas inside to push it back. The dough feels dense, cool and slightly clay-like rather than alive. This is not a slow rise; a slow rise still shows some change in four hours. This is a dough where fermentation is either not happening at all or is happening at a fraction of the rate you planned for.

The short answer

Three causes cover almost every case: the yeast was already dead, you killed it with hot water or by dropping salt straight onto it, or the kitchen is cold enough that the dose you used cannot do the job in the time you gave it. Proof a sample of the yeast in warm water to separate the first two from the third, then either restart with live yeast or move the dough somewhere warm and wait.

Why it happens

The yeast was dead before it went in

Instant dry yeast keeps for a year or more sealed and frozen, but an opened sachet left in a warm cupboard loses viability within weeks. Nothing about the granules looks different when they die. A two-minute proof test — 5 g of yeast and a pinch of sugar into 100 ml of water at 35 °C (95 °F), looking for foam within 10 minutes — is the only way to know, and it is worth doing before you commit 1 kg of flour. If the test fails, the fix is a purchase rather than a technique: the yeast guide covers which of the three forms to buy and how to store it so the same sachet is not the culprit twice.

You killed it in the mix

Yeast is a living organism with a narrow tolerance. Activity drops off above about 46 °C (115 °F), damage becomes significant by 49 °C (120 °F), and at around 60 °C (140 °F) the cells are killed outright. Water that feels properly hot on your wrist is already into the damage range. The other quiet killer is salt: sprinkled directly onto hydrated yeast it draws water out of the cells by osmosis and kills a meaningful fraction of them before mixing has even begun. Disperse the yeast into the flour or the water first, and add salt separately.

The kitchen is too cold for the dose you used

This is the case that fools people, because nothing has gone wrong — the maths is just against you. Yeast activity roughly halves for every 8–10 °C drop. A dough that ferments in 4 hours at 24 °C (75 °F) will need 8 hours or more at 16 °C (61 °F), and on a cold winter counter at 14 °C (57 °F) it can look completely static for an entire evening. Neapolitan formulas make this worse: they run as little as 0.2% instant yeast because they assume a warm room and a long window. Pair 0.2% yeast with a cold kitchen and you have a dough that will not be ready tonight.

Dose and timeline are one decision, not two. The dough calculator sets yeast against the schedule you actually have, which is more useful than copying a percentage from a recipe written for someone else's kitchen.

Fix it now

1. Proof a sample. 5 g yeast, a pinch of sugar, 100 ml of water at 35 °C (95 °F). Foam within 10 minutes means the yeast is fine and the problem is temperature. No foam means it is dead.
2. If the yeast is alive, get the dough warm. Find a spot at 24–26 °C (75–79 °F): an oven with only the light on, or a closed microwave beside a mug of hot water. Give it 2–3 hours and check for a domed top and bubbles at the container wall.
3. If the yeast is dead, restart the ferment rather than the dough. Dissolve 3 g of fresh instant yeast in 30 ml of water at 25 °C (77 °F), spread it over the flattened dough, fold it in, and knead 5 minutes until evenly distributed. Then bulk as normal — you have lost time, not flour.
4. Judge by volume, never by the clock. You want roughly 50–70% growth in bulk and a ball that holds a slow-filling dent. A dough that has more than doubled, lost its dome, and smells of alcohol has gone the other way and is now over-proofed.
5. Do not add extra yeast to speed up a cold dough that is working. You will get a fast, boozy ferment with no flavour development and a crust that tastes of yeast.
6. If you must bake it flat, press it thin, skip the thick rim, and treat it as a cracker-style base. A dense dough with a thick edge just bakes heavy and bready.

Prevent it next time

• Store yeast in the freezer in a sealed jar. It stays viable for well over a year and needs no thawing before use.
• Weigh yeast, do not spoon it. The gap between 0.3% and 0.6% of flour weight is 3 g on a 1 kg batch — invisible in a teaspoon, and the difference between an 8-hour and a 4-hour ferment.
• Use water at 20–25 °C (68–77 °F) in the dough. Reserve 35–40 °C (95–105 °F) for a proof test. If you cannot measure it, cool tap water is a safer error than warm.
• Keep salt and yeast apart until the flour is in. Yeast into the flour, salt into the water, or simply add them at opposite sides of the bowl.
• Measure your kitchen, not your recipe's kitchen. Below 18 °C (64 °F), raise the yeast or extend the schedule — for a same-day New York-style dough, 0.5–0.7% instant yeast and 5–6 hours is a realistic winter target.
• Check the dough at the halfway point. Fifteen seconds of looking at 2 hours tells you whether to intervene while intervening is still cheap.