Yeast for pizza dough: which form to buy, and the dose that sets the clock

What actually matters

Yeast is the cheapest ingredient in a pizza and the one that decides the schedule, which makes it the one worth understanding rather than guessing at. Three things settle the purchase: which form you buy, how much of it you use, and whether you have a step in your process where you can kill it.

The three forms are the same organism, dried to different extents. Instant dry yeast (IDY) is milled into fine, free-flowing granules and dried so that the cells rehydrate almost instantly. It goes straight into the flour or in at first mixing — no warm water, no sugar, no waiting for foam. Active dry yeast (ADY) is a coarser granule with a layer of dead cells around the outside; that layer is the reason the traditional instruction is to rehydrate it in warm liquid first, and dissolving it into the water is a genuine step rather than superstition for the older-style granules. Fresh yeast, sold as cake or compressed yeast, is about 70% water, crumbles like damp chalk, and is the form most professional bakeries used for a century. It also has the shelf life of a dairy product — a couple of weeks in a fridge — which is the reason it has largely disappeared from home kitchens rather than any deficiency in what it does.

The conversion between them is a weight ratio, not a swap. Because they contain different amounts of water and different proportions of living cells, a recipe written for one form has to be scaled to another. Instant is the baseline this site uses. For the same dough on the same schedule, active dry runs about 1.25 times the weight of instant, and fresh yeast about three times. In practice: 1 g instant is roughly 1.25 g active dry or 3 g fresh. Swapping one for another gram for gram is one of the two most common ways a dough ends up on a timeline nobody planned — under-yeasted with fresh, over-yeasted with instant. The dough calculator does this arithmetic for a batch, and it does it in the right direction.

The dose is not a fixed number; it is a dial that sets the timing. This is the part that separates a dough that peaks when you want to eat from one that peaks at three in the morning. Yeast quantity and fermentation time trade against each other, so a long ferment wants less yeast, not more. As instant, by flour weight: roughly 0.2–0.7% for a dough fermenting at room temperature on the day, around 0.3% for a 24-hour schedule, 0.2% for 48 hours, and 0.1–0.15% for a 72-hour cold ferment where the fridge is doing the timing. The cold fermentation guide has the full dose-to-timeline arithmetic. What makes those numbers usable at all is consistency — a dried yeast that behaves the same from batch to batch is what lets a percentage mean something, and it is the practical reason to buy one good pouch rather than whatever sachet the supermarket had.

One consequence of those percentages is a kitchen-equipment problem. At 0.15% of flour weight, a dough made from 500 g of flour wants 0.75 g of yeast. A scale that reads in 1 g steps cannot resolve that honestly, and rounding up to 1 g is a 33% overdose on a schedule where timing is the entire point. Either scale the batch up until the number lands somewhere your scale can read, or keep a pocket scale reading to 0.01 g for this one ingredient.

And then there is the way people kill it, which is worth stating plainly because it is so avoidable. Yeast activity falls away above about 46 °C (115 °F) and the cells are killed outright at around 60 °C (140 °F). Water that feels properly hot on the wrist is already inside that range. The whole warm-water proofing ritual — the one that exists because active dry needs rehydrating — is therefore also the step where home bakers most often destroy the ingredient they are trying to wake up, and then blame the flour. Buying a form that goes straight into the flour removes the step and the failure with it. The second quiet killer is salt tipped directly onto wet yeast, which draws water out of the cells; disperse the yeast through the flour and the two never meet undiluted.

The last thing that matters is not a specification at all. Yeast is alive and it has a clock running on it. An opened sachet that has sat in a warm cupboard since last summer is a dead culture that still looks exactly like a live one, and it is the single most common reason a dough does not rise. Whatever you buy, the storage plan is part of the purchase: sealed and cool until it is opened, then airtight and cold — the freezer is fine and it is where a large pouch earns its keep.

The picks

Three products, and only one of them is the general recommendation; the other two answer narrower questions.

The default is an instant dry yeast, for the reason that runs through everything above: no rehydration step means no opportunity to cook the yeast in the water, and a vacuum-packed pouch stored in the freezer removes the age problem that kills more doughs than technique ever does. The size is the honest catch. A pouch at this scale is years of pizza at the doses a pizza dough actually uses, which is a good thing only if you have the freezer space to keep it in and the appetite to work through it. Check the label variant before you buy: dry yeasts are sold in lean-dough and sweet-dough versions, and pizza is a lean dough.

The active dry yeast is not an upgrade on that and is not offered as one. Everything in the section above argues that instant is the better form for the schedules this site is built on, and carding an active dry does not soften the argument. It is here because one situation is common enough to deserve an answer rather than a lecture: your recipe calls for active dry by name and by weight, and you would rather buy the thing it names than run the conversion. If that is you, the conversion is above anyway and buying the thing named is one fewer place to go wrong. The part to be careful with is the water, not the yeast — the maker's own instruction is a window that sits below the temperature where activity starts to fall away, and the way people miss it is by judging the water with a hand instead of a thermometer.

The third is instant again, in a pack about half the size of one pouch, for a kitchen that does not want two 454 g (1 lb) pouches of live culture occupying a freezer shelf for years. Read its form from the maker rather than from the shelf a retailer files it under: it goes into the flour dry, exactly like the top pick. It also carries a dough-conditioner blend, and it is worth being precise about what is actually different there. Both instants carry ascorbic acid and an emulsifier; what this one adds on top is xanthan gum and enzymes. Both of those lists are the maker's own, and they sit on the same site — Lesaffre publishes ingredients for both brands on redstaryeast.com — so this is a real difference between two products rather than a difference in what anyone will admit to. A conditioner package is one more variable in a dough you are trying to keep repeatable, so knowing it is there beats discovering it later.