Pizza dough uses remarkably little yeast, often well under a gram for a batch of three pizzas. Understanding what that yeast is doing explains why the amounts are so small, why temperature matters so much, and why a dough is ready when it looks ready, not when a timer says so.
What yeast does in dough
Nearly all baking yeast is Saccharomyces cerevisiae. Modernist Pizza (2021), by Nathan Myhrvold and Francisco Migoya, describes two ways it gets energy. Right after mixing, while there’s oxygen in the dough, it respires. As the oxygen runs out, it ferments sugars into carbon dioxide and ethanol. The carbon dioxide dissolves in the dough’s water, then moves into the tiny air bubbles made during mixing, and the bubbles grow.
Its food is made in the dough. Yeast lives on sugar, and most of that sugar is made from the flour’s starch by enzymes, chiefly amylase. Modernist Pizza describes the supply as limited by the pace of the enzymes. Whatever sugar the yeast doesn’t eat is left to brown the crust; see the Maillard reaction.
It makes flavor as well as gas. The book notes that the dough’s lactic acid bacteria can turn some of the ethanol into acetic acid, and that the longer the fermentation, the more pronounced the yeast flavors become, because the microbes have more time to make aromatic compounds. Cold-fermented pizza flavor goes into that.
It stops in the oven. Yeast activity ends as the dough heats during baking; Modernist Pizza describes yeast as living until the dough reaches roughly 122 to 140°F (50 to 60°C). For mixing or rehydrating yeast, follow your recipe and the instructions for the yeast you actually use; the water temperature is not the same as the temperature of the mixed dough. In the oven, Modernist Pizza explains, the rise of a thin pizza is overwhelmingly due to steam, not the last of the yeast’s gas.
What speeds it up and slows it down
Temperature. “Yeast favors warmth over cold, as most living things do,” as Modernist Pizza puts it, and temperature is the most common way to control it. The warmer the room, the faster the dough ferments. That’s why recipes give a water temperature: Forkish mixes most of his doughs with 90 to 95°F (32 to 35°C) water to reach a dough temperature of about 80°F (27°C), assuming a 70°F (21°C) kitchen. In a hot kitchen, he suggests water 10 to 15°F (5 to 8°C) colder, aiming for a dough in the low 70s°F (low 20s°C), or a little less yeast.
Salt. Salt slows fermentation by putting osmotic pressure on the yeast cells. Modernist Pizza recommends 2 to 2.5% for seasoning and warns that above 3%, fermentation slows to a detrimental degree. Without salt, the book says, the yeast eat so fast that the dough ferments too quickly and bakes to a pale crust.
Sugar. A little sugar is food, but a lot is not: above about 6% in the dough, Modernist Pizza says, sugar pulls so much water from the yeast cells that growth and fermentation slow dramatically.
Instant, active dry and fresh yeast
| Instant | Active dry | Fresh (compressed) | |
|---|---|---|---|
| Moisture | About 5% | About 8% | About 72% |
| How to add it | Straight into the dough, or dissolved in the recipe’s water | Dissolved in warm water first | Dissolved in the recipe’s water |
| Keeps | 2 years unopened in a cool, dry place; 1 year refrigerated once opened | 1 to 2 years unopened; 4 months refrigerated or 6 months frozen once opened | 2 to 3 weeks from manufacture, refrigerated; about 1 week once opened |
From Modernist Pizza, volume 1, pages 293–296.
Instant yeast has finer granules and more active cells than active dry, and it’s what Modernist Pizza, Forkish and the Pizza Planner use by default. You can add it straight to the dough, but Modernist Pizza prefers to dissolve it in room-temperature water for better dispersal, and says that if you don’t, proofing will likely take 20 to 30 minutes longer.
Active dry yeast granules are coated with dead cells, up to 25% of their weight, so there are fewer live cells per gram. It has to be rehydrated: Modernist Pizza uses water at 104 to 110°F (40 to 43°C). Too cold is a problem too: soaked in cold water, the damaged cells leak glutathione, which makes the dough sticky and slack.
Fresh yeast is traditional in Naples, and most pizzaioli there still use it. Modernist Pizza’s objection is consistency: many blocks carry no manufacture or expiry date, so you can’t tell how lively they are. Its verdict on fresh against instant: “There isn’t a difference in the resulting pizza.”
Freezing. Forkish keeps instant yeast airtight in the refrigerator for about 6 months, and passes on Jeffrey Hamelman’s experience of yeast kept wrapped in the freezer performing consistently for years. Modernist Pizza notes that freezing costs some viability, and suggests using 25% more yeast than the recipe calls for if you store yours frozen.
Converting between forms
| To replace 1 g of… | Instant | Active dry | Fresh |
|---|---|---|---|
| Instant | – | 1.33 g | 3 g |
| Active dry | 0.75 g | – | 2.28 g |
| Fresh | 0.33 g | 0.44 g | – |
These are Modernist Pizza’s conversion factors. The AVPN’s regulations and Forkish both use the same 1 to 3 ratio between dry and fresh yeast, and the Planner converts the same way when you choose active dry or fresh. Example: 7 g of fresh yeast becomes about 2.3 g of instant or 3.1 g of active dry.
How much yeast pizza dough uses
Modernist Pizza uses tiny amounts, 0.01 to 0.08% of the flour weight, for doughs left at room temperature, and more, 0.25 to 0.5%, for doughs that spend a long time in the refrigerator, because the cold slows the yeast so much. Forkish’s recipes show the same pattern. All of these use 500 g of flour and instant yeast:
| Forkish recipe | Instant yeast | Schedule |
|---|---|---|
| Saturday Pizza Dough | 0.3 g (0.06%) | 2 hours bulk, 6 hours in balls, at room temperature |
| ”I Slept In But I Want Pizza Tonight” Dough | 0.5 g (0.1%) | Warm 100°F (38°C) water; 1½ hours bulk, 4 hours in balls |
| 24- to 48-Hour Pizza Dough | 1.5 g (0.3%) | 2 hours bulk, then 16 to 48 hours in the fridge |
| 48- to 72-Hour New York Pizza Dough | 1.2 g (0.24%) | 2 hours bulk, then 48 to 72 hours in the fridge |
The Planner’s three schedules for round pizzas follow these families: same-day at 0.06% instant yeast, overnight (about 24 hours in the fridge) at 0.3%, and long-cold (about 48 hours) at 0.24%. For same-day pan pizzas it follows King Arthur Baking’s recipes, which use more yeast.
Weigh it. Forkish notes that a ¼ teaspoon of instant yeast weighs very close to 1 gram, and some of his recipes call for as little as 0.1 g, so a scale that reads to 0.01 g is worth having. The Planner flags any yeast amount under 1 g for the same reason.
Ready means ready, not the clock
Rooms, fridges and flours differ, so a schedule is a starting point. Forkish’s sign of a mature dough ball is one that has expanded, shows small bubbles of gas, feels soft and relaxed, and stretches out easily; too little time leaves it elastic and the crust dense. Too much time, he warns, and the dough “expands too much, loses its integrity, and gets too full of hot air.” Each stage of the Planner’s schedule comes with a readiness cue to check against. If it went too far, see over-proofed pizza dough, and for timing, how long to proof pizza dough.
Sourdough: a different culture
A sourdough starter, or levain, ferments with wild yeasts and lactic acid bacteria rather than a single commercial strain. Modernist Pizza notes that commercial yeast gives dough a neutral flavor, while a levain imparts a sour one, and that the bacteria’s acids also strengthen the gluten. It also points out that pizzerias around the world overwhelmingly use commercial yeast, because it’s simple and reliable and a levain’s flavor is often dominated by the toppings anyway. More in sourdough pizza dough.
One belief worth dropping: that very low-yeast dough is easier to digest. Modernist Pizza looked for evidence and found none, partly because the yeast dies in the oven. See pizza myths debunked.
Sources
- Nathan Myhrvold and Francisco Migoya, Modernist Pizza (2021), volume 1, printed pages 133 (digestibility), 292–297 (how yeast ferments, controlling it, the three forms of commercial yeast, storage, blooming, conversion factors, amounts for room-temperature and refrigerated doughs, fresh against instant yeast), 302 (levain and lactic acid bacteria), 312 (salt), 315 (sugar) and 362 (oven spring).
- Ken Forkish, The Elements of Pizza (2016): chapter 3 (dough and water temperatures, adjusting for climate, mature dough balls), chapter 4 (“Yeast”: instant yeast, storage and measuring) and chapter 6 (Saturday Pizza Dough; “I Slept In But I Want Pizza Tonight” Dough; 24- to 48-Hour Pizza Dough; 48- to 72-Hour New York Pizza Dough).
- Associazione Verace Pizza Napoletana: International Regulations, 2024 edition (the dry-to-fresh yeast ratio). Checked October 14, 2026.