Tools
Convert fresh, instant dry and active dry yeast
My protocols are written with fresh yeast. To replace it, I divide the amount by 2.5 for instant dry yeast and by 2 for active dry yeast, which has to be reactivated in warm water first. This converter works in both directions.
Three forms of the same yeast
Pizza yeast is a microscopic fungus, Saccharomyces cerevisiae. In the shops you find it in three forms, which do not hold the same amount of active yeast per gram:
| Form | Looks like | Amount compared with fresh | Particularity |
|---|---|---|---|
| Fresh | A block | Reference | Crumbled or dissolved in the recipe water |
| Instant dry | Small, slightly elongated granules | A half to a third; I divide by 2.5 | None |
| Active dry | Granules of dormant cells | Divided by 2 | Reactivated 10–15 min in water at 30–43 °C (86–109 °F) |
Why I use 2.5 for instant: it is the equivalent I apply in practice, 3 g of fresh for 1.2 g of dry, and it sits in the middle of the usual range. The converter also shows that range, a half to a third, so you know where you stand.
Active dry yeast
Active dry yeast is not a chemical leavener: these are real yeast cells, simply put to sleep. To wake them up you need warm water, between 30 and 43 °C (86–109 °F), and 10 to 15 minutes of patience.
Whatever the yeast, the dough must then come out of kneading at 23–25 °C (73–77 °F): the water temperature of the recipe is what gets you there.
My doses in fresh yeast
My protocols are expressed in fresh yeast, as a percentage of flour weight. The dough calculator applies them directly and also shows the dry-yeast equivalent.
| Protocol | Fresh yeast | Instant (÷ 2.5) | Active (÷ 2) |
|---|---|---|---|
| Traditional 24 h | 0.3 % | 0.12 % | 0.15 % |
| Contemporary direct | 0.2 % | 0.08 % | 0.1 % |
| Biga, in the preferment | 0.4 % | 0.16 % | 0.2 % |
| Biga, at the final mix | 0.1 % | 0.04 % | 0.05 % |
With such small amounts, a misreading is costly: 0.08 % of 1 kg of flour is 0.8 g. Weigh to a tenth of a gram.
What if the timing changes?
Conversion answers only one question: how much of another yeast does the same job. If you change the resting time or the room temperature, the dose itself has to change: that is what the yeast amount calculator is for. To understand what happens during fermentation, read the page on yeast types.
Frequently asked questions
How much dry yeast replaces 10 g of fresh yeast?
About 4 g of instant dry yeast, or 5 g of active dry yeast. For instant, the usual range is a half to a third of the fresh amount, so 3.3 to 5 g; I use 4 g.
How do I use active dry yeast?
Its cells are dormant. Reactivate them for 10 to 15 minutes in water between 30 and 43 °C (86–109 °F) before adding them to the dough, and use half the fresh-yeast amount.
Why do you need less dry yeast than fresh?
All three forms contain the same yeast, Saccharomyces cerevisiae, but dry yeast is more concentrated: you need 2 to 2.5 times less to replace fresh. Once the conversion is done, the rest of the protocol stays the same.