Yeast in pizza dough — the guide

Instant dry (IDY) — fine granules, no proofing needed: whisk it straight into the flour. The calculator’s default, and the easiest to find.

Active dry (ADY) — coarser granules in a dormant coat. Wake it in a little warm water for 5–10 minutes before mixing.

Fresh yeast — the soft, crumbly block from the refrigerated aisle. Smells like a bakery, works beautifully, lives maybe two weeks.

Sourdough starter — not a product but a pet: wild yeasts and bacteria you keep fed. Brings acidity and depth, and you need far more of it by weight.

Swapping types? These weights raise the same dough:

On a spoon: dry yeast runs about 3.1 g per level teaspoon, sourdough starter about 15 g per tablespoon — the same conversions the calculator’s “cups” mode uses.

Yeast activity roughly doubles every 7 °C. An hour at 27 °C ferments about as much as two at 20 °C; an hour in a 4 °C fridge counts for about 12 minutes. Impasto converts your whole plan into these “effective hours,” then sets the dose inversely: fresh yeast % ≈ 6 ÷ effective hours.

The anchor worth memorizing: a 24-hour rise at 20 °C wants about 0.25% fresh yeast of the flour weight — a true pinch. Halve the time, double the pinch.

Notice the direction: more hours, less yeast — and more flavor. The long rows taste better, because fermentation builds what no bigger pinch ever could.

At fridge temperatures (2–8 °C) the yeast nearly stops: a full day at 4 °C counts as only about 4.9 effective hours. That’s the trick of cold fermentation — you park the dough where it barely rises, while enzymes keep quietly turning starch into sugar, flavor and better browning.

Stages simply add up. A short rise on the counter, then one to three nights in the fridge, is the classic plan — the calculator’s fridge toggle does exactly this arithmetic and writes the schedule around it.

Practical notes: ball the dough before the long nap so it’s ready to stretch, and give it 1–2 hours back at room temperature before shaping — cold dough fights back. Buonanotte.

Want the day-by-day — 24 vs 48 vs 72 hours, fridge temperatures, rescue plans? The cold fermentation guide goes deeper.

Kitchen scales shrug at anything under a gram. Either get a 0.1 g pocket scale (cheap, sold for jewelry and espresso) or use spoons: the 24-hour plan above needs about 0.4 g of IDY for 500 g of flour — roughly ⅛ tsp.

And don’t agonize. A little over and the dough is ready a bit sooner; a little under and it’s a bit later. Watch the dough, not the clock: ready dough has roughly doubled, jiggles like a panna cotta, and smells sweet — not boozy.

A preferment is a head start: the night before, you ferment part of the flour with a crumb of the yeast, then mix it into the final dough. It buys aroma, extensibility and color for zero extra effort — just planning.

Poolish is the liquid one — equal weights of flour and water (100% hydration). It bubbles like a batter and makes dough silky and extensible. Biga is the stiff one — around 45% hydration, a shaggy crumble. It builds strength and a deeper, almost nutty perfume.

In the calculator’s Pro mode, the preferment takes 10–60% of the flour and about 40% of the yeast, and the schedule gains a “night before” step. No preferment with sourdough — the starter already is one.