Fresh vs instant vs active-dry yeast

The three yeasts

Fresh yeast (cake or compressed) is moist, crumbly, and traditional in Italy — it has the shortest shelf life. Instant dry yeast (IDY) is a fine granule that mixes straight into the flour, needs no proofing, and keeps for months. Active dry yeast (ADY) is a coarser granule that was traditionally bloomed in warm water first, though many modern brands can go straight in.

How to convert between them

By weight, the rough rule is: IDY ≈ ⅓ of fresh, and ADY ≈ 1.25 × IDY (about 40% of fresh). So 9 g fresh ≈ 3 g instant dry ≈ ~3.75 g active dry.

This calculator's yeast percentage assumes instant dry yeast. To use fresh, multiply the gram amount by about 3; for active dry, by about 1.25.

Which should you use?

For most home bakers, instant dry yeast is the easiest and most consistent — it's what we'd recommend. Fresh yeast appeals to traditionalists and gives a subtly different aroma. Use active dry if that's simply what you have on hand.

Storage and freshness

Keep dry yeast sealed and cool; refrigerate or freeze it for a long life. Fresh yeast lasts only about two weeks refrigerated. To test older yeast, stir a pinch into warm, lightly sugared water — if it foams within 10 minutes, it's alive.

Amount depends on time and temperature

There's no single "correct" yeast amount: it depends on how long and how warm the dough ferments. Less yeast plus more time means more flavor. A long, cool cold ferment uses far less yeast than a fast warm proof — the calculator can estimate this from your schedule.